Planescape: Torment is the pick of the IE games, certainly recommended if you've enjoyed the two Baldur's Gate games (and expansions).
Wizardry 8. I highly recommend this game. The negative aspect of the game is that the graphics and sound are very backward. They claimed the game was in development for 5 years. That's a very bad idea. Other than that, the game is excellent and very challenging even if you play in novice mode.