The only way to sign up and participate is via the Genes for Good Facebook app. However, Facebook does not have access to your health information. If you provide a saliva sample and have your genes analyzed, your information is kept securely on a University of Michigan server. The test is free, but you do have to complete 15 health history surveys and each health history tracking survey at least twice to qualify. The health surveys are short, simple, and interesting. There is one, that is a short test for colorblindness, another one asks what your height and weight is, etc. I did all of the surveys and found them to be very quick and easy. I spent about 30 minutes on one day doing them and another 30 minutes on the next day to complete them and was told at that point, that I qualified to get the free spit-test kit.
The researchers say that in return for your voluntary participation, they will provide information about your genetic ancestry and estimated proportion of Neanderthal DNA, and you will be able to download your genetic raw data. It doesn't look like they will be able to provide you with specific individual health related genetic information, but once you obtain your raw data, you can run it through a database such as SNPedia http://www.snpedia.com/index.php/Promethease to get user friendly health related genetic information.
The health tracking surveys are meant to be used routinely. You can answer short surveys about cold/flu, alcohol use, mood, activity, sleep, stress, and weight daily or a few times a week. The graphical tools built into Genes for Good allow you to track your progress and use the information to improve your health. You can compare your ancestry and health results to other participants. I've looked at some of the health survey graphs, comparing my data with other participants and found it fascinating. Health tracking results can also be downloaded.
Any questions you might have are probably answered here http://genesforgood.sph.umich.edu/faq
I'm not sure how the gene analysis via Genes for Good compares to the one done by 23andMe, which costs $99, but I'll keep you posted.
Looks like they have about 5000 participants already. Not sure how many participants they have funds for, so if you want to participate, you should probably do it quickly.