I bought the Serenity RPG for shits and giggles and just based on a quick read, it doesn't look too bad. I'm not sure how the system would hold up when played, but since I haven't played any RPGs in ages, it's a moot point for me. My favorite RPGs were: WEG Star Wars 2nd Ed Paranoia Twilight 2000 2nd Ed Shadowrun 1st Ed (before those fucking Phyical Adepts) Top Secret/S.I. I never did get into the D&D type games, but Paranoia was fucking hilarious to play.
Did anyone ever play that Call of Cthulhu game? It was based entirely on a % system, ever skill roll you make is between 1-100. I rolled a 1 while trying to drive our getaway car.
Yeah, got a love a game that tracks your sanity. Just as many characters go insane over the course of the game as get killed - and there's a lot of the later! Call of Cthulhu and Paranoia are classics.