Out of those 3 options, I'd stick with Google Groups. It's easy to moderate/manage and search through content. Facebook Groups seem very distracting to me and u

Out of those 3 options, I'd stick with Google Groups. It's easy to moderate/manage and search through content. Facebook Groups seem very distracting to me and until they fine tune the notifications part, its a wee bit gimmicky. Yahoo groups, well I haven't used that in a while but it certainly was susceptible to spamming a lot more than google groups I've run.