What to advertise on a mainstream site?
 

I have a site I just threw up a couple of years ago, and didnt really do anything more with... I just checked it now, and it turns out it has 1500-2000 uniques per day. It's a joke site.

Obviously I can not throw adult stuff on there, any ideas?

Oh btw, it has AdSense on it now. Which makes a couple $ every day it seems. Probably would do better with something else.