5. FileZilla
Despite a similar sounding name, Filezilla is not connected to Mozilla in any manner! Its a free and cross-platform FTP software, consisting of FileZilla Client and FileZilla Server. Binaries are available for Windows, Linux, and Mac OS X. It supports FTP, SFTP, and FTPS (FTP over SSL/TLS). As of now it is one of the top 9th most popular download of all time from SourceForge.net with 240.6M.
6. Audacity
Audacity is a free open source digital audio editor and recording computer software application, available for Windows, Mac OS X, Linux and other operating systems. Audacity was started by Dominic Mazzoni and Roger Dannenberg at Carnegie Mellon University. Alone on SourceForge the software has around 80.5 million downloads. The application also won the SourceForge 2007 and 2009 Community Choice Award for Best Project for Multimedia. Users can record and edit live audio by cutting, copying, splicing and mixing sounds and can also convert ageing tapes and records into digital format.