Alternative to Facebook Groups

I've been on a course for people interested in running their own business. (Which I will be posting about later as I wasn't expecting the trainer to read my feedback whilst I was still there) and I and the other participants wish to stay in contact. There's only twelve of us, so I don't need a heavy duty solution, but I want something that has similar functionality to Facebook Groups, isn't Facebook Groups and is free.

Any suggestions? It should preferrably but exceedingly easy to sign up to as there is a large range of tech saavy.

Any suggestions?