This how to from Learn to preserve is a great one for preserving melon. It dehydrates well and ends up being like a candy sponge. I made some last year and we ate the whole watermelon in 2 days. It is that good. I would like to do a few this year as watermelon comes into season so I can hopefully put some up for when there are no watermelons.
http://www.learntopreserve.com/other-fun-stuff-to-preserve/2010/9/5/watermelon-jerky-trust-me-on-this-one.html