My personal list would be something like this:
1. Apocalypse World as an RPG with "standard" DM-players split, action oriented but with good exploration of character relationships
2. Kagematsu because it's one of the games that made me *feel* most
3. A Penny for My Thoughts as something that's VERY different from your standard RPG
4. Microscope similarly to Penny, is a very particular game
5. Trollbabe because it's a game that gives the player a lot of power, which they often don't have in your standard fantasy RPG.
6. Enter the Avenger because it's a very accessible and easy game, and can be played in a very short time, with a complete story.
7. The Room (by Ariele Agostini) as another game that's easy to set up, it's similar to a larp and can be played only once
I'm sure I missed a whole lot of titles. I feel I should also include some LARPs, but unfortunately I don't know many. I wanted to add a more classic GMful game, maybe Archipelago, but the other games kinda cover that part. I also feel Murderous Ghosts should have a place in the list, but I wouldn't know what to take away ^^