In Austin, Texas, there are several online communities that bring local people together that I'm familiar with, such as
HerDomain, which is for women in Austin who work in Internet tech, or want to; and
CommunityTech-Texas, for those interested in the "digital divide" in Texas. The big difference in these local online communities versus national or international communities is that you will probably actually meet at least a few of the people on the list face-to-face at some point, if you don't know them already, and that can certainly affect the way people post (ofcourse, for some, it has no affect at all...).
Too often, people talk about how the Internet brings people from far away together; it can also do a great job of further networking the members of a local community together.