I'd try to pick up Batman: Year One, by Frank Miller. Some of Miller's best work, IMO, and a really good Batman story. Aside from that, I don't know. The recent Jeph Loeb Hush storyline has been collected in trades (two, IIRC), and I loved it, but fan opinion of the storyline is very divided- people either hate it or love it.
I personally haven't read too much Batman since the Pre-Crisis stuff (with the exception of Year One and Hush).
Dark Knight Returns (again, Miller) is supposed to be awesome (I've only skimmed it), but I wouldn't say it's a good introduction to the character.