A lot of stuff. Mostly, their blogs and documentation of their study-related projects is in german ( which is not a big deal if you're german .. haha ), but I think that it's interesting to take a look at what they are doing.
Tommy was or is ( he claims to be at 90% ) busy coding some kind of document managing system in Java, you can read all about it in his blog. He seems to be a bit focused on glass effects, though. And his blog is in english, so good for you.
Good boy Johannes, who is just like me, long-haired and changing his blog URL quite frequently, is very ambitious: he's doing a game engine in C++. He points out what he's doing very detailed in his new blog at mumpitz.p-shuttle.de. Unfortunately, it's in german..
Käse ( best nickname ever, means just "cheese" ), who just got married, congratulations, creates some musical visualisation using Process. Read about it here. He's not updating it too frequently, but the stuff present, especially the preview movie are quite amazing.
These are only the projects of the three guys I'm talking to frequently. I don't have one so far, but I'm on it, trust me!