Using Yahoo or Google Groups for Marketing

Do you belong to any groups? Yahoo groups, Google groups…etc?

I subscribed to many groups and I get the digest of the group discussion every day. A lot of the people who participate in the groups are your highly targeted customers. For instance, if you join a soap making group, everyone who joins the group is soap maker or learning to be a soap maker. The people who started the group are usually experts or even owners of soap making stores.