Yahoo! Groups Yahoo! Groups allows you to create and manage online email communities in areas such as Recreation and Sports, Entertainment and Arts, Hobbies and Crafts, ...
http://groups.yahoo.com/
Google Groups Google Groups allows users to start their own email discussion groups and message boards, and browse archives of Usenet groups.
http://groups.google.com/
Flickr: Groups Flickr is almost certainly the best online photo management and sharing ... Group Guidelines Browse all Groups. Groups are a fabulous way to share photos and ...
http://www.flickr.com/groups/
MySpace Groups Join or create a group on MySpace. Browse the list of groups by category and language.
http://groups.myspace.com/
Most Popular Groups on imeem Watch Video Clips, Stream Music, View Photos, Post to Blogs & Forums, Join Groups, Browse Profiles and more on IMEEM, the best of social media!
http://www.imeem.com/groups
Moderator Central - Yahoo! Groups Sharing the latest and greatest Yahoo! Groups news and providing a channel for moderators to connect with one another to ask questions, share advice, and find resources.
ICQ Groups - ICQ.com Support Groups. Grief. Disorders. Disabled. Reducing. weight. Family Matters ... ICQ groups allow you to connect with others that share your interests.
http://groups.icq.com/
Groups - Windows Live The shared calendar makes it easy to see who's busy when, and plan your next group event. ... discussions, send e-mail, or IM with the whole group at once.