PostBooks topped the download list at Sourceforge again. PostBooks is a free open source accounting oriented ERP application based on PostgreSQL, C++, and Qt. There are two commercial versions with one aimed at manufacturing.
PostBooks is owned by a commercial organisation an they make their money selling their commercial upgrades. Lots of projects work this way. The biggest problem is the limit to the range of enhancements the community can supply without competing against the commercial versions. As an example, manufacturers will have to upgrade to the commercial manufacturing version and may never see a free version with enough functionality for manufacturing.
Sourceforge houses about half of the open source projects. The biggest projects tend to have their own web site. If you are the top application in a category on Sourceforge, you might be the top application across the Internet or you might trail behind several big applications hosted at their own Web sites. PostBooks is more than top of a category, PostBooks is often the top download for the whole of Sourceforge, making Postbooks a very popular application.
PostBooks is available at sourceforge.net/projects/postbooks.
Would I use it?
I will not use PostBooks for two reasons. I will not use open source projects that are artificially limited by a commercial version. I prefer a PHP and Web based application so I can read the code and build enhancements if I need something extra.