Of the ones not mentioned already I'd have to go with
Johnny Quest
The Weird Al Show
Charmed (I like the song)
Josie and the Pussy Cats
Mission Impossable
Ranma 1/2
Stop That Pigeon!
Scooby Doo
Magilla Gorilla
Doctor Who
Teen Titans
Battle of the Planets
Edit: My bad, it's "A Difficult Situation." That's usually played when Inuyasha's getting his tail handed to him, be it by Sesshomaru or Ryokuotsei or whoever.
The theme from Exo-Squad.
The opening theme from Tour of Duty (first two seasons...yes, it's Paint it Black, by the Doors, but it's still cool)
The theme from Gargoyles
Apparently, I like horns and percussion. Who knew?
Teen Titans
Hong Kong Phooey
Rockford Files
Fall Guy (I'm the unknown stuntman...)
Inspector Gadget
Monk (It's a jungle out there, danger everywhere...)
Gravitation (Super-Drive)
Ranma 1/2
Firefly
Babylon 5
Buffy the Vampire Slayer
Bob Newhart Show
Cheers (esp. the long version)
Mary Tyler Moore Show
Dick Van Dyke Show
Wings
Firefly
Star Trek: TNG
X-Files
Highlander
Star Trek: DS9
...in pretty much that order. Firefly's theme song is unbelievably good, and out of those five it's the one that most evokes the show for me. Awesome song.