Since this group is for gamers about games, let me get started.
My favorite system right is D6 Fantasy. I enjoy fast, abstract combat and simple, easy-to-use systems that I can modify without breaking. To that end, I also like Cyberpunk 2020 and have been looking into Savage Worlds.
Maid: RPG because it's fast, random and ridiculously funny.
It's a game that's modeled after anime sitcoms. You play a group of anime-style maids in service to the "master" (the GM) who is a rich guy with a mansion. You try to gain the master's favor by doing all of the often ridiculous housekeeping tasks he asks (I remember once my maid party had to go to the ancient ruins under the mansion to destroy a lovecraftian horror that was messing with the water).
You can generate a whole game and its situations by rolling on random tables, and everything is d6-based. You also generate characters, their personalities and their backstory entirely randomly too.
Favor is like XP. You can use it to boost your scores. You can also spend favor to direct the story for a bit, like causing a random event. If you "die" you can lose favor and a bit of your scores to return to the game. If you lose all your favor, you are fired.
There's a misconception that the game is inherently romantic or perverted, which it isn't unless you want it to be.
Dark Heresy and Rogue Trader, both set in the Warhammer 40K universe.
The setting is so dark, it's pitch black; any given object is probably going to kill you, corrupt you or drive you insane; just about every enemy is tougher then you are and most importantly, it has some pretty cool sci-fi trappings. It's like CoC, but more over the top and with a lower PC body count.
I'm really just a masochist. I mean, 40% success rate can be considered normal in DH sometimes.