I've recently been listening to a lot of music that ends up being the theme for many a great show. For instance, my favorite song right now (as you can hear on my page) is "A Beautiful Mine" by RJD2 and Aceyalone.
Most recently the opening titles to HBO's Trueblood has a great song (and I'm not to partial to country) and really creepie visuals.
Some other favorite of mine included the opening of House with Massive Attack's "Teardrop"
And the opening of the new series "Fringe" by an artist I have no clue of.