Balls of rice. With stuff inside. If you've been to Japan, you know them, love them, and probably eat them 18 days a week.

Snap a photo of a rice ball on your phone (try to get one pic of the wrapper and one of the inside), write the name of the place you bought it and the name of the onigiri in the subject line, then write a one or two line review and send it to post@onigiri.posterous.com!