The Storyteller system. Basically, this is what White Wolf keeps cranking out settings for - their World of Darkness setting.
Let's see - Vampire: the Masquerade, Wraith: the Oblivion, Changeling the something or other, Werewolf: the Rage, Hunter: the Reckoning, Mage: the Ascension. I think I got most of them - but not all, I don't think. Scary.
The basic idea is quite simple. Roll a number of d10 determined by whatever you try to do (usually there's a skill of some sort + an attribute in dice pool) against a target number determined by the GM. Sorry, Storyteller. Count successes, and see how well you did. Ones are special (bad), as well as tens (good).
I haven't really played the Storyteller systems all that much - but enough that I can get sarcastic about it. However, it plays fairly well - provided you don't like much realism in your games. Why?
Well, it all boils down to statistics. Even someone ridiculously skilled at what they do can fail at even the simplest tasks as long as there's a test rolled. Sooner or later an awful lot of ones are rolled, and they cancel successes. Not only that, but because of the statistics of the thing, it is good to be very poorly skilled at whatever you do if you attempt something with a high target number. You see, the more dice you roll, the larger the chance of getting at least one 'ones' roll, and that cancels the success that you might have. Better with 0 successes than -1 success...
Me, I like Street Fighter: the Storytelling game. Less angst, and more martial arts. I'm easy that way. Furthermore, we've (we? a lot of people, and you'd better believe it) added a few features from the various other Storyteller systems, and it plays rather well. I think so, at least. But more about that in the Street Fighter section.