TwitPic

TwitPic lets you share photos on Twitter. It hosts them and gives them short URLs.

This is on the short list of functions Fred Wilson singled out for slaughter.

TwitPic is bootstrapped but profitable on over $2 million/year in revenue (half of which is profit!). If TwitPic gets crushed by Twitter, at least founder Noah Everett will have banked some cash for a rainy day.