How many do you know? And do you know how many of them are true vs. made up or partly inspired by true events?
I know a lot of the famous ones and some lesser known ones as well, and I've seen the Revealed series and read through the snopes site and Jan Harold Brunvand's encylcopedia; hardly an expert but I know a lot of them: hook, obviously false, baby-sitter and the man upstairs, false but in part definitely possible, killer in the backseat, possible, stoned baby-sitter cooks child in oven, not exactly true but these microwave-baby killings seem to more than compensate for that unfortunately.
I do find a lot of the stories and their origins to be very interesting and also I find it interesting how many are often used in movie dialogues and TV shows and some of them, I did not know at the time were urban legends, like in Gremlins the dead dad in the chimney dressed like Santa Claus story, or in the Blob, the boy buying condoms (or the pharmacist thinks so anyway) for a date finds out the pharmacist who gave them to him is the father of the girl he's dating.