Pinko Marx
Banned
The minigames in pokemon stadium.
COD Zombies is probably a big one.
Mario Kart Battle Mode is usually more fun in a group than the main Grand Prix mode.
Mirror's Edge's campaign is maybe a 6/10, the time trails are pretty much the best thing of this generation.
Coin Rush in New Super Mario Bros 2 is fantastic, especially some of the DLC levels.
Unfortunately, its amazingness is violently undercut by a lack of leaderboards or even proper personal per-stage high score tracking.
I wish it was a standalone.COD Zombies is probably a big one.
Not sure if it counts, but custom games in Warcraft 3. Spent so many hours on various themed TDs and game modes.