My favorites are:
Inspector Morse (absolutely haunting, though my husband hates it when I play it because he knows morse code and the code in the theme drives him nuts)
Mike Hammer
And I really like the Angel theme.
I can’t believe no one’s said Airwolf yet. That’s an awesome song! Almost as good as Knight Rider!
I adore Malcolm In The Middle 's theme by They Might Be Giants.
Dangermouse had a great theme (He’s the fastest he’s the greatest he’s the best!) and any song, theme song included, from Animaniacs totally kicks animated butt.
Ditto on Cheers and X-Files.
My faves: Hawaii 5-O, Jeffersons, and Gary Shandling.
The worst is probably All in the Family. I heard you can beep the Rockford Files song on a telephone, anyone know the numbers?
Ahem.
Speed Racer.
How can anyone forget Speed Racer?
I like the themes to King of the Hill, CSI, The Odd Couple, and Deep Space Nine.
My absolute favorite TV show theme, however, is the hauntingly beautiful opening song of Ghost in the Shell: Stand Alone Complex.
I never watched it much, but I thought the theme to Cowboy Bebop was pretty great. I’ll second Dangermouse. And I vaguely recall really enjoying the theme to MANTIS.
One that everyone my age seems to know by heart is the theme to Hey Dude. It wasn’t really good, though.
It hasn’t yet been mentioned, but I love the theme to The Adventures of Pete and Pete (“Hey Sandy” by Polaris). It’s a really good song by itself, but its feel matches that of the show perfectly.
Ah, yes, thanks for catching that! It’s funny…I googled “Roger Daltry” to make sure I got the name right, and just assumed it was since a bunch of hits came up, including IMDB. You’d think I would have noticed, though, that IMDB spelled it “Daltrey”. :smack:
Conspicuously missing from our list is the theme from The Love Boat.
While not techinically a theme song, I love the song that played at the end of every The Incredible Hulk series starring Bill Bixby and Lou Ferrigno. It’s probably one of the most haunting songs I’ve ever heard and even as a child, I thought it showed the isolation and sadness that David Banner must’ve felt.
Polaris did a lot of songs for The Adventures of Pete and Pete. What a great show. The other Nickelodeon show theme song that everyone remebers…sing it with me!
“Camp Annawanna, we hold you in our hearts! And when we think about you…”
I love Family Guy, but the theme song really bothers me whenever it comes on or when I watch my DVDs. No matter what volume I have my tv set at, it always sounds too loud. It’s too upbeat.
I adore the theme song from The Critic. I’ve searched online for days, weeks trying to find a full version I can buy or download, but alas, one doesn’t seem to exsist. I know it must, you can hear where the song is cut during the opening, but it’s just nowhere! Still, I will listen to this song as I drive through a big city in a fall morning someday.
I also like the theme song for ChiPs. the show I can take or leave, but I’m always sure to listen to the themesong before changing the channel.
My friend and I both think the theme to Trigun is quite nice.
I think the song is pleasant enough, but it was a really bad choice for this show. It’s quirky and lighthearted when the show is quirky but serious.
The worst: ** The People’s Court** Admit it. I win.
“…What a world! What a girl! What a life!” (Or was that last word wife?
The best theme: Henry Mancini’s Mr. Lucky
I can’t believe nobody’s mentioned the theme from Swat Cats. Absolutely amazing…I especially liked the part where the lead guitar kicks in, and also the part where one of the rockets from the Swat Cat’s jet misses the target - “Crud!” 
“The Venture Brothers” has a great theme song. It’s an instrumental.
I also really like the “Teen Titans” theme song.
I can’t believe nobody (including myself) has mentioned Suicide Is Painless, the song from MASH. That’s an absolutely amazing theme song. How much more pathos could possibly fit in a 45 second theme?
Can’t say they’re really good but I have to mention anything you can sing in full-on lounge singer voice. Obviously The Love Boat springs to mind, but my favorite is The Patty Duke Show’s theme in lounge style. But they’re coooousins–Yeah!–identical cousins and I bet you’ll fi-yiiind…
No animals were harmed in the singing of this song.
I really don’t want to mention the worst ones because the ones I hate most will lodge in my head all day. Oh shit. Too late. Doo-do-do-do-doop Inspector Gadget! Doo-do-do-do-doop…woo-hoooo!
Please tell me you’re kidding.
Most of my favorites have already been mentioned, but here’s a few that haven’t:
Adventures of Brisco County Jr. – Probably more people would recognize it as the “Olympics promo” music, but it was originally written for the short-lived but great Bruce Campbell series. Like the “Magnificent Seven” theme, it just sounds like a Western.
Renegade – Yes, the mindless '90s action series starring Lorenzo Lamas. I am ashamed to say I watched it, but you have to admit it had a great theme by Mike Post. Actually, Mike Post did a LOT of cool themes, including . . .
Magnum, P.I. – A true '80s classic! One of the top 10 themes of all time, in my book.
Worst: The Patty Duke Show Having it stuck in your head can cause one to consider suicide by shotgun.
The Batman theme, if it’s prepared.