I don’t watch much TV these days. I used to watch more and have found that good intro/title sequences hold as many memories for me as the show.
I remember dozens of fun (Friends), catchy (The Jeffersons), cool (Knight Rider, Airwolf, Hawaii Five O) themes from earlier, but the best intros are a bit more recent and manage to capture the vibe of a whole show in under two minutes.
It wasn’t easy to pare it down to five, nor rank them, but here are mine:
Honorable mention for the mega-nostalgia factor: Hill Street Blues