Brust's Jhereg series offers a ton of possibilities. Lots of different types of magic, good fights, plenty of fluff, plenty of politics, it's all really there for someone to write (which I believe Monte Cook once said he'd like to do, but I may be remembering that wrong). He has more than one protaganist group going (if you also look back in time). I think these books could be played without feeling like you'd need to play the protagonist(s) from the books.
Obviously Midkemia/Kelewan should be a game, but I understand that the author believes his house rules could NEVER be done with real core rules (this one always cracked me up) and has rebuffed all attempts to license his books.
I'd like to see some rules for the coldfire books (where you imagine it, it can become real), but it would take a lot to create a whole RPG from this series.
The Deed of Paksanaarion (sp?) books would make a good RPG, but again you'd need to do some major work, and these books have one central protagonist, so I'm not sure it would work.