Google
Groups - Originally called Deja.com, it is a full-featured
community site. based on the older Usenet newsgroup platform.
In addition to a new interface and features, it is another
source of AdWords revenue.
MSN
Groups - Using the near-ubiquitous Passport login system,
MSN members can also create areas for like-minded people
to interact.
Yahoo
Groups - Yahoo members can create public or private
areas where topical enthusiasts can post messages, images,
share information, chat and more.
