I've never met anyone off the internet, but I was a wingman for my friend who had met someone. He met her through a chatroom (which after seeing his debacle, I wouldn't recommend IMO), and she wasn't exactly who she said she was.
I have friends who do the Match.com thing and they seem to like it. I would say there is a huge difference between internet dating websites and chatrooms.
Feifer and Wyndemere, congrats on your love's. I, in no way meant to say that it couldn't happen, just was sharing the experience my buddy had. Of course, he jumped the gun a little and met this girl the next day...oops!