I never knew who the hell “Frency” was
Damn it, that should be “Frenchy”. Apparently he was a French guy. Or he might have been Canadian. Beats me.
I think my all time favorite is Doctor Who.
In the short but sweet category it’s definately the theme to The Hitchhiker’s Guide to the Galaxy.
For cheesy good fun: The Greatest American Hero
Flashbacks to a happy childhood: Star Blazers
Creepy beauty: Twin Peaks
and if 'm in a bad porn movie or 70s flashback mood, it’s gotta be the theme to What’s Happ’n?
Ducktales theme!! The cartoon also had great backround music in the show.
Gummi Bears had a good theme too!
Simpsons’ theme.
Ren and Stimpy had some WEIRD backround music and sound.
Cool McCool, Saturday morning kid’s cartoon created by Bob “Batman” Kane in 1967.
Yet another late-1960s spy genre spoof…the opening theme featured a particularly tasty LSD-flavored electronic organ as a background to McCool being menaced by his rogues’ gallery of bizare arch-villains.
As much as I liked Christopher Franke’s work on B5, the one that really impressed me was Evan Chen’s music for the follow-up Crusade. Although there are some out there that credit his music with killing the show, I loved it.
wait, i’ve got another one.
Homicide had some great songs that played during the show, that really fit (created?) the mood. Where else would you hear Soul Coughing’s Super Bon Bon during a investigation scene?
I have The Shield to thank for introducing me to the Magnetic Fields.
I love the Buffy the Vampire Slayer theme song.
I always want to sing along with the That 70s Show theme song.
Zoggie, the opening theme is called “Moonlight Densetsu,” and it is catchy; I’m listening to it as I type. Oddly enough, I’ve never even seen the program, only read the manga. Another catchy magical girl theme is “Wedding Wars,” the second opener to Wedding Peach, and the only song not done by the voice actors, who can’t sing. 
No The Tooth, you’re not, but I thought about them and decided (just MHO) that they wouldn’t be as cool without the voiceovers. I.e., the music itself isn’t the only thing going for them.
I absolutely loved Buffy: The Musical <sad, pathetic> I even have the Mp3’s burned to CD so I can listen in my car</sad, pathetic>
Okay, I’ll say it. I think the theme to Alias is pretty sweet.
“The Rock Cried Out, No Hiding Place” from B5 is one of my favorite TV moments ever.
People, PEOPLE, PEOPLE!!!
The theme from ALF! Hands down the greatest TV theme song ever.
Higher Ground has a good theme tune, and the music played in the program is always good too. Same with Smallville & Dawsons Creek.
Ren and Stimpy was the first show that conciously alerted me to how important music and soundmix was to a TV show… the way it used classical music and comic stings, (not to mention excellent use of the surround sound field) has always impressed me greatly.
That being said, I also think Cowboy Bebop has an excellent soundtrack, but (no offense to the great Yoko Kanno)-- Hellsing’s music blows me away completely. It’s eclectic and insane, with mixtures of techno, classical and even old-school horror movies thrown in for good measure.
Much of the greatness of Ren and Stimpy came from the use of using light, jolly production music where it shouldn’t be. In an essay in The Cartoon Music Book, Joseph Lanza calls this “gale-storming” (as opposed to “mickey-mousing”-apparently, Gale Storm was a sickeningly sweet actress). Jolly music shouldn’t accompany a vomiting cat or similar gross-out image, but it does. And for some reason, it fits.
Specifically in the Sopranos’ Dave Davies’ ‘Living on a Thin Line.’
I don’t know if you’re talking specifically about themes, or just music used in the show, but Scrubs always picks great music to use in theirs, especially the selections that are played over the ending scenes of an episode – often montage scenes.