A corollary of this is that the theme song to Star Trek: Enterprise would make a good sitcom theme song. I lack the raw materials and skill, but you could get some mileage out of playing the Enterprise theme song over the opening sequence to Perfect Strangers.
Another thing I didn't pick up on until now was that sitcom theme songs never mention the name of the sitcom, [Update: not true, see comments] probably because they were commissioned long before the name of the sitcom was finalized, and probably because they were written long before that and shopped out to multiple sitcoms. Also, a common trope in these songs is to talk about how the world has gone to pot and how the relationship formed by the sitcom's main characters (family/friendship/bar) is the last outpost of civilization. So you could switch a lot of theme songs and it would work fine.
As a test I improvised the worst imaginable theme song, for a sitcom called "Healthy, Wealthy, and Wise". It was terrible.
(6) Sun Nov 18 2007 09:49 It's A Race Condition:
Lately Sumana has been obsessed with the theme songs to sitcoms. I heard some of these songs when I was a kid but they all merged into one. Understandably so, now that I hear them again from the next room. One thing I didn't pick up on back then was that the lyrics of many of the songs are made of mortared-together cliches. Now, I've written songs out of cliches, but I try to put my own spin on them or juxtapose them in interesting ways, and more importantly my songs don't become cultural touchstones.