* Thrawn Trilogy. Thrawn Trilogy! THRAWN TRILOGY!!!
What he said, plus I'll say it again:
THRAWN TRILOGY/HAND OF THRAWN DUOLOGY!!!!
Ok, so now that that's out of the way here's a few more I think are worth the read:
The New Jedi Order series (Yuuzhan Vong series)
The Courtship of Princess Leia
I, Jedi (actually never read it, but I've heard enough about it that I'm confident recommending it)
Darksaber
The Black Fleet Crisis trilogy
The Corellian Trilogy (I especially like this one. Third behind Thrawn and NJO for me)
That's pretty much all I've read so far. Don't have a library close to read the others.