wefeelfine.com

Online family tree wikis or wikigenealogy's. I know of 3 of them at the moment:
wikitree.org
rodovid.org
werelate.org

It might be a little confusion choosing which to use. There have been moves to merge these 3 projects but I dont know the current status of that move. I discovered wikitree first and started using it. My advice to anyone is to stick to one of them and hope that they will all merge soon.

There are many online family trees out there but I prefer a free wiki-based version versus a restrictive commercial version.