Something to play with on Mac?

So I'm looking for something to do on my mac on slow nights at work. I have video game emulators, I replaced my superdrive with an extra hard drive, have virtual machines running Windows that I can connect to.

I need something to mess around with when I'm bored instead of blindly surfing the net.

Any ideas?

Sketchfighter 4000 Alpha! I love this game. The company who publishes it is going out of business, but I think you can still buy it-- provided it looks interesting to you.

http://www.ambrosiasw.com/games/sketchfighter/


EDIT: There's a free trial for it too.

It's pretty cool. Thanks. Been playing it for a bit.