What are the most popular Sites about Semantic Web Open Source Projects?

Is there any venue to meet people interested in doing open source projects of semantic web? (A kind of sourceforge, but especialized).

There is also SemWebCentral at http://www.semwebcentral.org/, which hosts a number of Semantic Web tools. From the web site:

SemWebCentral is an Open Source development web site for the Semantic Web. It was established in January, 2004 to support the Semantic Web community by providing a free, centralized place for Open Source developers to manage Semantic Web software and content development.

I know I've seen quite a few groups on Meetup, just search "semantic web".