There is a site I have found called myfamily.com which is really meant for family tree groups. I have a family tree group on MSN which I have moved to myfamily.com (maually) because its is very much like msn in the way it operates. It has message boards, photo albums, document storage, etc etc. You can create custom pages as well. In fact its the most like MSN I have found but better. And you get up to 100mb each for storage, a lot more than on MSN. I know I sound like I'm trumpeting this site, but having used it for a week or so, it really works well.
Although its aimed in the first instance at family tree groups, it actually can be used for any type of group. It may be worth a look.
Stu