Implement a system where you can text message the code on the bottom of the cap or inside a badge and see if you win that way the User will not have to wait to get a computer. Sure you won't be able to get all that valuable information you would when
they would register normally, but gee golly it would be convenient.
Then they couldn't target ads and suggestive sell you crap. If they are giving away a trip to <insert location> courtesy of Orbitz.com or something part of the argeement with Orbitz to help sponsor the prize is all that advertising they can put in front of
you by having to go to the contest site and enter your code. In the end it is all about the company and sponsor and nothing about you. Just my opinion.