Ludum Dare is generally good for quality games. Knytt and WaDF are also awesome.

Uhhhhhhh, other things: Cave Story (obviiiii), Chzo Mythos + Art of Theft, Rescue: the Beagles, Warning Forever, rRootage, noiz2a, Facade, La Mulana, Fraxy, Tumiki Fighters, Immortal Defense, Notiu-Love and Noitu-Love 2, Clean Asia, War 2199, Little Fighters 2, Death Worm.