Horrible waste of time, about a horrible waste of time
A fun little site is Television Tunes, which has all the original songs from old TV shows, from specific seasons. You can hear how they started taking the chicken-pickin' out of the intro to Dallas in the early '80s, and such. Interestingly, over the decade or so that Hawaii Five-O was on, they never tweaked their theme at all. When you're putting greatness out there, it needs no adjustment.
But the best part is the stupid (yet ingenious) Name That Theme Song Game that they have on it. I was sure that I would suck at it, but I was surprised at how high I listed on their high-score list.