"Sponsormymelon.com!" yelled some guy a few years back and since then the idea has been top of mind.. (sorry).
The Guardian spoofed it when the Cunning crew said they'd sell it... And now, you can find quite a few on Ebay. Here you can Advertise on this mans forehad!, or if you want to *Advertise your logo or website domain on this guys forehead!, here's one that reads " Advertise Your Logo on my Ass (or Forehead)" oooh, cheeky, how about Advertise Your logo on 3 C.I.K.TV staff forehead and help som local kids TV program get some much needed equipment. Seems a worthy cause.