I just watched the first series of Dexter after a recommendation by someone here in this forum. Very good indeed. The site I mentioned a few posts previously has series two, but I am going to wait for the dvd shops to have it as I like to watch them continuously. Another series I enjoyed was Californication, starring David Duchovny , well worth a look.
Also, for those of you who aren't sick of cop shows, there's one called 'The Wire' which is kind of good. I haven't seen it on dvd, only as a torrent. Worth a gander.