From James Bowes' article, A code hosting comparison for open source projects:
If you're starting a new open source project, or open sourcing some existing code, you'll need a publicly accessible location for the version control system holding your code (if you're not planning on setting up a publicly accessible VCS, reconsider; no public source control is a red flag to potential contributors). You could set up your own repository hosting, but with so many companies and groups offering existing setups and services, why not use one of those and save yourself some time?
Read more on SourceForge, GitHub, Google Code, Gitorious, and Bitbucket from his article.
If your not familiar with Codeplex it's Microsoft's free open source project hosting site.
What qualities do you look for in a repository? Share in the comments or tweet to us @opensourceway.