I don't know if these have been mentioned, but...
House, MD (looks like the entire series.. I'm halfway through it again already...)
Life - Kind of a fun, campy police drama.
The Glades - Same thing.
The Finder - This was a good show, but got cancelled when Michael Clarke Duncan died.
Chuck - A pretty far-fetched but fun "undercover CIA" spy show. But it's got Adam Baldwin, so it's cool.
MI-5 - Killer drama about the British Secret Service.
Lie to Me - Tim Roth is one of the coolest mofos on the planet. Crime drama based on the science of "microexpressions".
Mythbusters
Destination Truth
Criminal Minds: Suspect Behavior
North Woods Law - Reality series about the Maine Warden Service. Cool show.
Firefly AND Serenity - Nerdgasm. Browncoats unite!
There are so many cool documentaries. I find myself watching mostly science-y ones.. animals, rain forests, Earth stuff, universe stuff, ancient Egypt.. blah blah blah.