Here's a fun (and seemingly easy) outdoor project to try: Make a Hammock in 3 Minutes. The idea is to use a 60x126" tablecloth as the body of the hammock, a couple of loops of rope to whip the ends, and a few minutes of your time to assemble the setup. Give it a watch:
For $10 in supplies, it's hard to go wrong with this project. And worst case scenario, you have a massive tablecloth you can use, well, on your table.
I love idea of co-opting formal tablecloths for outdoor use. You just never know where handy supplies are going to come from.