I think they're great. I love Christmas lists, birthday lists, etc (handwritten ideas, not a registry for Christmas and birthdays). I think it's a nice way to let people know what you want and need. It's not like people are obligated to purchase from the lists, though. If I know the couple well enough to get them something really personal or to put something together, I will...but, if I'm not sure, it's nice to have a guide.