I like the idea of the caricature artist but I'm kinda artsy and it fits me. I had a friend suggest to me of doing a snow cone stand and have flavors that consisted of not only the theme (wedding cake flavor is popular in the South) but my colors as well (sage and ivory with bursts of lavender here and there - hence, honeydew flavor with cream and maybe grape).
Surf board with ocean backdrop--was a beach wedding
Life size cut outs with face missing-out your own in it, that was crazy fun
Also little people in costume that danced I forget what caractores they were.
Shilouette cutter. Those guys are amazing, they take the tiny little pieces of black paper and use tiny little scissors to cut shilouettes of the guests, which they mount on a card for them and let them take home. the always goes over well and it's a great momento!
Polaroid camera guest/photo book. Have an attendant take someone's picture and the person can scribble a cute message on it. When done place the reception pictures in your photo album. Perhaps hire an illusionist to do card tricks instead of playing a slide show.