Writing Contests

Does anyone know of any good writing contests for elementary kids? I have a couple of kids who are just EXCELLENT writers, and I'd love to try to get them published or a prize or something. I've looked at the Instructor website and also Mailbox, but I didn't find anything. I've also just searched on the web, but I'm not real confortable with that b/c I wouldn't know of the reputation.

Any suggestions?