Dexter is good, I think he's totally INTJ though.
nBattlestar Galactica was good too. Baltar ftw. And the hot cylons.
Breaking bad is another series I follow. Has some good 'OMG' moments. Come on season 4... ><
Spartacus was pretty fun, so much blood! Bit too much sex though. I know! I can't believe I'm complaining either.
edit: oh yeah, and Firefly. I keep trying to forget about it since it never got the showing it deserved.
Flight of the Concords, So glad I got to see them rocking out a hall in NZ. a lot of local humour
older shows:
The office (UK)
Band of Brothers
Freaks & Geeks. I have a crush on the protagonist still
And for anime:
DBZ
Death note!
Zoids: New Century Zero
Shows I'm undecided about:
Ergo Proxy: Seems like a whole bunch of nothing happens for 2/3 of the series, cool the rest of the time though.
Dollhouse: A good concept ruined further into its run.
Chuck: It's kinda good for light watching, even if it's pretty ridiculous. And it's given me a new appreciation for Blonde.