“With or without the lyrics, that is”
The Avengers
Due South
King of the Hill
Rockford Files
The Bob Newhart Show
The Odd Couple
3rd Rock from the Sun
Simon and Simon
Prisoner
Mission Impossible
I’ll second Hogan’s Heroes and Barney Miller.
Taxi.
Room 222
Justice League
Gunsmoke
Bonanza
Here in Canada we have a show called ‘W-5’, and its theme music is Fool’s Overture by Supertramp. I nominate it - the song sounded even better as the theme of a TV show than it did as a song, and it’s a great song.
Also a fan of the Doctor Who theme, as well as the original Space:1999 score.
- Tamerlane
I like:
Mystery
Vision On
Sanford and Son
Alfred Hitchcock
“The Ballad of Serenity,” which was the theme for Firefly, performed by Sonny Rhodes.
It manages to capture at once the major themes of the show: Chinese and American West hybridization, having everything taken away from you, the importance of independence, and so forth, while also serving as a beautiful song about the show itself and the trials it went through before its eventual (hopefully temporary) cancellation.
*Take me out into the black,
Tell them I ain’t comin’ back
I don’t care, I’m still free
You can’t take the sky from me. *
I’ll list some of my favorites (In no particular order):
“Dragnet”
“Cowboy Bebop”
“The Greatest American Hero”
“Knight Rider”
“CSI”
How come nobody has yet mentioned “The Magic Roundabout”?
A link to a media player file is on http://www.rsc.co.uk/zebidee/history.htm
I wonder if the original French broadcast used the same time?
Aqua Teen Hunger Force
Closing themes that rock: Powerpuff Girls & Spongebob.
In the late 1980’s I would watch th enew MightyMouse on Saturday mornings. Of course the original song was there ("Here I come to save the day!), but there was also an amazing male chorus version of the sone that was atonal. It was just amazing. I would love to have a recording of that music and would be forever in t debt to the person who provided it to me.
As is Pete Carpenter’s. 
Aqua Teen Hunger Force is quite awesome. Cowboy Bebop, also already mentioned, rules.
But my all-time favorite is the Clone High theme. You may remember the extremely-short-lived-but-hilarious animated series on MTV. I think Abandoned Pools did it. Fire up Kazaa and give it a listen, it’s excellent.
“Police Woman” with Angie Dickinson had a good theme. The opening of that show gave my teenaged self funny feelings belowstairs.
Peter Gunn easily takes second on my list, but I have to agree with vibrotronica–Tank! from Cowboy Bebop is better. It’s almost too close to call, though.
“Number one in the hood, G”
Funny that there is a deep rap hatred in SD, yet the theme to “Aqua Teen Hunger Force” gets mad props, as well as it should.
But the all time best is “The Jeffersons”.
The theme music from The Huntley-Brinkley News Report. It was the 2nd (3rd?) movement of Beethoven’s 9th Symphony.
Second choice: Peter Gunn, Henry Mancini
Third: Route 66
Fourth: Six Feet Under
Fifth: Mission Impossible or Twilight Zone