Find out what Sub Saturday is and how to participate:

http://chippermonkey.net/forums/viewtopic.php?f=83&t=3294

List of Game Modes:

Things to keep in mind and unless otherwise stated:
- When restricted to items under X Tag, you may grab the components of that item so long as you plan to complete it. (Ex. You may pick up a Zeal for Trinity Force, however you may not pick up another Zeal to build into a Phantom Dancer until you complete the Trinity Force)
- Trinity Force is AD (Banned for Hybrid), Lichbane is AP (Allowed for Hybrid) just for clarification
- Resistances is both Armor and Magic Resistance.

1. Game Mode: Those Fists Were Fast As Lightning.
   Details: Only champions with the Tank Tag are allowed, Madred's Bloodrazor must be your first item (must be completed before picking up any other item), Afterwards you must build items under the Attack Speed Tag.
   All Consumables are allowed (After Madred's Bloodrazor is complete.)
2. Game Mode: All or Nothing!
   Details: Only champions with the Carry Tag are allowed. Only Carry builds (No items with survivability stats: Resistances, HP)
   All Consumables are allowed.
3. Game Mode: The Pen Is Mighter Than The Sword.
   Details: Only champions with the Melee Tag are allowed. Only build items under the Ability Power Tag.
   All Consumables are allowed.
4. Game Mode: Ninjas vs Pirates vs Ninjas vs Pirates.
   Details: You can only pick champions that are a Ninja (So far: Akali, Kennen, Shen) or a Pirate (So far: Gangplank, Miss Fortune) Alternatively, if you have a Pirate or a Ninja skin for a champion, you may use them instead.
5. Game Mode: You Must Be This Short To Fight
   Details: You can only pick Yordle champions. (So far: Amumu, Corki, Heimerdinger, Kennen, Poppy, Rumble, Teemo, Tritana, Veigar)
6. Game Mode: I NEED MANA!!!
   Details: Only Manaless champions (So far: Akali, Dr.Mundo, Garen, Katarina, Kennen, Lee Sin, Mordekaiser, Renekton, Rumble, Shen, Tryndamere, Vladimir) One summoner spell must be Clarity. Only build items that under the Mana or Mana Regen Tags
   All Boots and Consumables are allowed.
   (Thanks boynameddan)
7. Game Mode: Everybody's Super Sonic Racing!
   Details: Choose a champion with a Movespeed increase ability or passive. Ghost & Flash are your required summoners spells. Only build items under the Movespeed Tag
   No Consumables
8. Game Mode: Mirror Match Up
   Details: Before the match begins each team takes turns choosing a champion until 5 are chosen. then each team decides on one summoner spell each. Once the lineup has been chosen both teams must choose those champions at the champion select and use the two selected summoner spells.
9. Game Mode: Upclose and Personal
   Details: Only champions with the Melee Tag are allowed (Nidalee is banned.) Items with Ability Power on them are also banned (Exception: Trinity Force.)
   All Consumables are allowed.
10. Game Mode: Tank Busting
    Details: Each team must consist of 4 champions with the Tank Tag and 1 Kog'Maw. Builds are free reign.
11. Game Mode: If You Can Dodge A Wrencth You Can Dodge A. . .
    Details: Each team must have a Nidalee (Wrench), and only champions with line skill shots are allowed, you can only level up and use those skills, supplimental mode "a" is in effect. Only items that provide damage/ap are allowed (Avoid stats like HP, Armor, Resist, Life Steal, Spell Vamp.) Boots are allowed, but following the same rules. One final note if an item has an active effect on it, you are allowed to use it. Below is the list of champions and their builds:
    Champs allowed -
    Amumu Q - AP (Not Recommended)
    Blitzcrank Q - AP (Not Recommended)
    Brand Q - AP
    Dr. Mundo Q - AD
    Ezreal Q - AD
    Kennen Q - AP
    Leblanc E+R - AP
    Morgana Q - AP
    Nidalee Q - AP (Wrench, HAVE ONE OF THESE)
    Rumble E - AP
    Urgot Q - AD
12. Game Mode: The Forgotten
    Details: Only champions from Elementz Solo Que Tier - List 3  are allowed.
13. Game Mode: I Love Freebies
    Details: Only champions that are free this week are allowed.
    (Thanks ColdSnow)
14. Game Mode: Ability Restrict
    Details: At the loading screen teams choose one ability on each champion that cannot be leveled up or used the entire match. (Ban one ability on the champion vertical to you)
    (Thanks Dragonspride)
15. Game Mode: Global ultimates
    Details: Only champions with global Ultimates allowed (So far: Ashe, Ezreal, Gangplank, Karthus, Shen, Soraka)
    (Thanks Dragonspride)
16. Game Mode: Assassin's Brotherhood
    Details: Only the champions (Akali, Evenlynn, LeBlanc, Shaco, Twitch, Vayne) are allowed.
    Oracles Elixirs are banned, but pink wards are allowed. 
17. Game Mode: Spam Sequence
    Details: Only build items under the Cooldown Reduction Tag.
    (Thanks WindShaman)
18. Game Mode: It's A Tarp!
    Details: Only champions with trap/turret abilities are allowed. (Caitlyn, Heimerdinger, Nidalee, Shaco, Teemo, Maokai) Only build items under the Ability Power Tag. TrinityForce is banned.
    (Thanks ghostmexi007)
19. Game Mode: Clickmania
    Details: Only build items that have an Active (Zhonya's Hourglass, Yomou's Ghostblade, etc)
    All Boots and Consumables are allowed.
    (Thanks MihkelS)
20. Game Mode: Alphabet
    Details: First person on each team does a hard random, then the next team member after them chooses the champion that follows the first champion alphabetically (So if the first person gets Irelia, and if the next person doesn't have Janna they would choose Jarvan. If you pass Z start back over at A) and this continues throughout each team.
    (Thanks Falris)
21. Game Mode: Trying On Grassy's Shoes
    Details: Pick one of the following characters and build/play it as such -
    - Ashe, build AP or Hybrid
    - Annie, build AS
    - Anivia, build Movespeed
    - Blitzcrank, build AD
    - Caitlyn, build AP
    - Cho'Gath, build Attack Speed
    - Corki, build AP
    - Evelynn, build Tank
    - Ezreal, Build AP
    - Galio, build AD
    - Gangplank, build AP
    - Gragas, build AD
    - Heimerdinger, build AD or Hybrid
    - Janna, jungle, build AD
    - Jax, jungle, build Tank
    - Soraka, build AD or Hybrid
    - Sona, jungle, build AP
    - Tryndamere, build AP
    - Veigar, build Tank
    - Udyr, build AP or Hybrid
    Consumables are allowed in all builds :P
    (Thanks Dragonspride)
22. Game Mode: I support. . . WITH MY FISTS!
    Details: Only champions with the Support Tag are allowed. Get items that have an attack stat on them (ex. Attack Speed, Attack Damage, Critical Strike Chance, Armor Penetration), AND SUPPORT!
    Items with AP on them are banned, however All Consumables are allowed.
23. Game Mode: The Beasts Within
    Details: Only champions allowed are animals/beasts/etc, no humans/yordles. (Casseopia is allowed)
    (Thanks Falris)
24. Game Mode: Fetch Me My Cane
    Details: Each team must choose one of the two setups: (One male and Four females) or (One female and Four males.)
    (Thanks Coldsnow)
25. Game Mode: Naked Brawling
    Details: No items. Period. I have reached my maximum power level! If the game lasts 40 minutes, everyone MUST port back to base and spend all of their current gold on items (You are only allowed to purchase this one time, so be sure to spend all of your available gold!)
    (Thanks Natoba)
26. Game Mode: The Only Skill Worth A Damn (aka. Team DotA)
    Details: You can only level your champion's ultimate (R Skill).
    (Thanks Someoned)
27. Game Mode: The M Team?
    Details: Teams can only be made up of champions whos names start with the same letter.
    (Teams so far: A, K, M, S, T ) Example: A-Team - Akali, Alistar, Amumu, Anivia, Annie, Ashe
    (Thanks Falris)
28. Game Mode: Assassinate
    Details: Only champions with the Assassin Tag are allowed.
    (Thanks ColdSnow)
29. Game Mode: The Longest Game Mode EVER (aka Turtle Wars)
    Details: Only champions with a shield ability (That absorbs damage) are allowed and you can only level up that shield ability, also one of your summoner spells must be Fortify. The game will be restricted to using only middle lane, however porting back to base and Snowball items are allowed. *MORGANA IS BANNED*
    (Thanks Srahman)
30. Game Mode: Omnomnomnom
    Details: No Items. Only Consumables Allowed.
    (Thanks Mystriopolis)
31. Game Mode: Big Bruiser Blitz
    Details: Only champions with the Fighter Tag are allowed. All must built pure tank (Items containing HP and Resistances), no AD or AP are allowed (Atmas is banned
    (Thanks Natoba)
32. Game Mode: I HAVE THE POWER!
    Details: Only champions with the Mage Tag are allowed. Only build items under the Ability Power, Mana, Mana Regen, and Cooldown Reduction Tags while avoiding stats like HP, Armor, Resist, and Spell Vamp. Boots are allowed, but avoiding the same stats.
    (Thanks CynicalShin)
33. Game Mode: Role Reversal
    Details: Your character will build according to its Tags. If your character has multiple tags, the priority on Tags is Tank/Fighter > Mage > Support > Assassin/Carry. (Ex. Chogath has the Tags Tank and Mage, but according to the priority he would be considered a Tank/Fighter for this game mode)
    - Tank/Fighter - Build items under the Ability Power, Mana, Mana Regen, and Cooldown Reduction Tags, while Avoiding the stats HP, Resistances, Damage, and Critical Strike.
    - Mage - Build items under the HP, Armor, and Magic Resistance Tags, while Avoiding the stat Ability Power.
    - Support -  Build items under the Damage, Attack Speed, Critical Strike, and Life Steal while Avoiding the stats Ability Power and "Aura Items" (See Assassin/Carry.)
    - Assassin/Carry - Build "Aura Items" (Abyssal Scepter, Aegis of the Legion, Shurelya's Reverie, Soul Shroud, Stark's Fervor, Will of The Ancients) You are also allowed to build: Rylai's Crystal Scepter, Zhonya's Hourglass.
    * All boots and consumables are allowed for all roles.
    * Use this link to help you find out what Tags your champion has: http://na.leagueoflegends.com/champions

Supplimental Game Modes:

(Game modes that can be combined with any others)

1. Game Mode: All Middle
   Details: All Middle , No Fortify *summoner spell*, No Snowball items (leviathan, soul stealer, sword of the occult)No returning to base and may only purchase items after your death. *Final Note* You are allowed to defend the top and bottom base turrets (aka inhibitors & their turrets).
   
2. Game Mode: Legendary Mode Unlocked
   Details: Required Summoner Spells: Revive + Teleport.
3. Game Mode: Uncle Cheap Bucks
   Details: You cannot buy anything or build anything containing an item worth OVER 1000 gold. (Keep in mind you can buy items and recipies worth 1000 gold Ex. Archangels)
   Example: You can build zeal (Total cost: 1195, Individual Pieces are less than 1000 however you cannot use zeal in any recepies)
   (Thanks Someoned)
4. Game Mode: Shared Loot
   Details: No two champions on the same team can posess the same item.  (Ex: A team can only have one boots of swiftness, one madred's razor, etc. This is also the case with component items, so only one person at a time may have a negatron cloak in their inventory until they upgrade it. So be sure to hit Tab before buying items!)
   (Thanks Persequor)

Quick Game Modes:

1. Game Mode: Protect The King!
   Details: Both teams nominate a king, kill the enemy king to win. Be sure to protect your own!
2. Game Mode: Push, Push, Push, Push, Push!
   Details: All of blue team goes top, All of purple team goes bottom both teams push and whoever can destroy the enemy nexus first wins. Defending is not allowed. Fortify is banned.
3. Game Mode: Baron Race
   Details: All lanes + Jungle are open, engage Baron when he spawns at 15, the team to kill baron is the winner.

Have a game mode suggestion?

Post it in this forum! http://chippermonkey.net/forums/viewtopic.php?f=83&t=2775