If you'd like to make up to $17,000 over a 90 day period, sign up for NASA's Bed Rest Study.
You get to do fun things like lay in bed (without getting up) for 90 DAYS, eat a "carefully controlled diet", lay with your feet elevated above your head and participate in various " tests to find out changes in the state of your bone, muscle, heart and circulatory system, and nervous system, as well as your nutritional condition and your ability to fight off infections."
It's tempting! Except, if I'm going to lay in bed for three months, I'd better be able to eat anything I want. So, no deal for me... But here's the application if you're interested.
Good article on wiredscience.com about it also!