Just found out that TF2 is now free from these comments. I just finished creating a Steam account and it'll be about 3-4 hours before TF2 is installed. It's one of those games that I really wanted to try at the time, but never got around to. Finding out it's free and active is more than enough to get me to give it a try.
I think the main reason I never tried it is that I didn't realize that it still had an active community, and I've been tired of paying for games I get bored with easily. Also, though the game may have slipped to 10 bucks, I never even knew it was that cheap.
On topic, I tried a trial of WOW about a year ago and played about an hour before I got tired of it. Took me about 2 weeks before I completely deleted it though. I have no intention of downloading it again due to the changed terms. I know I'll get hooked if I play long enough, but while I'm still clear eyed it just doesn't seem to be that fun of a game.