I'm not so good at assigning group projects (mostly because I side with student opinions of them and mostly because I'm a control freak and like to do things myself, so I don't like working in groups). But. I realize I may be doing the students a disservice by not allowing them the periodic struggle of working with others.
I've come up with this sheet that I think I'll add to my next group project. I'm SURE I'll assign one. Soon. This year. Some time.