SourceForge is the world's largest open source software development web site.
Their tagline is "SourceForge: Find and Develop Open Source Software."
The open source software project category covers from Games/Entertainment to Software Development then to ERP.
Did i tell you that as of February, 2009, more than 230,000 software projects have been registered to use their services by more than 2 million registered users. Yes that a great number :O.
PS: This is about page of the site.