The HabForum

http://www.keepmovingforwardsweeps.com/

Here's a link to a contest which has a trip to Space Camp as the grand prize. Only open to U.S. residents but I didn't notice if there was any age restrictions.

I didnt see any age limit either so i went ahead and entered and answered a trivia question for a bonus entry aparently you can get bonus entries each day by answering questions. They are science stuff but atleast the first one wasnt space related.