Does he like me or not? What does this guy want from me?

He used to smile at me in college and say hi (nervously) sometimes. Then we went out with a few people to a club and he came along and we had a good time. However, after this he started to ignore me and act like I didn't exist. But I would still see him looking at me sometimes. Two days ago I saw that he sent a request for me to add him on facebook...what does he want?