ok i'll suggest my personal fav's
i'd guess you'll already have Throne of Bhaal being such a BG2 fanatic so i won't suggest that.
morrowind is a great game, loads of gameplay and great fun
Deus Ex is amazing. its my favorite game of all time. i've played though twice even though its more the kind of game to play though only once (not so many side quests just lots of ways to complete each missions)
Dungeon siege is ok if you want a no-brainer run kill run kill kinda game. loads of people like it but if you like BG2 that much (like me
) i woyuldn't suggest this game
NWN is also good even though i've only really just started playing.
The Final Fantasy series is great. i've played final fantasy 7 for over 450 hours. its one of the greatest games i've ever played plot wise and the char upgrade system is fun
if you want a really sick game you could download Thrill Kill like my brother did. the game was never comercially released for the playstation and has such characters as "The Imp"-a midget on stilts and a guy holding a severed leg and wearing an "I love barbique" apron
i can't really think of any other games right now