I think these are the guys that are responsible for a huge portion of the funny photoshopped stuff on the net.
Fark.com
Look for the Photoshop logos in the thread list. I even think they are the ones who created the tourist guy standing on top of the WTC.
Fark.com doesn't make any of the stuff on their site, they just link to all sorts of crazy stuff on the net....including lots of photoshoped pictures.