• Study (most unlikely)
• Browse whatever site, e.g. LJ, tumblr, Facebook
• Clean my room
• Read a book (could be combined with studying) or pretty much anything I got
• Browse eBay (or any other site that sells stuff of interest)
• Watch Gossip Girl (or whatever other show I'm addicted to at the time)
• Chat

And what am I going to do now at 1AM in the morning? Clean my room.