Sylpheed
Sylpheed is a free and open source, multi-platform, simple and lightweight email client
Evolution
Evolution is a free and open source application for managing personal information: mail, contacts, calendar, tasks, and notes
gmusicbrowser
gmusicbrowser is a free and open source software for listening to audio, a music player for large collections
Lollypop
Lollypop is a free and open source music player and music collection organizer
ANoise
ANoise is a free and open source user-friendly app that allows you to play ambient/background noises
MoonPlayer
MoonPlayer is a free and open source video player for playing and downloading online videos from YouTube, Youku, and iQiyi, as well as local videos
Wolfenstein: Blade of Agony
Wolfenstein: Blade of Agony is a free-to-play first-person shooter similar to Wolfenstein 3D, Medal of Honor, and Call of Duty, but with a more dynamic game in the spirit of Doom
JuK
JuK is a free and open source audio player, music manager, and audio file tag editor
Asunder
Asunder – free and open source graphical audio CD ripper and encoder for Linux
Spivak
Spivak is a free and open source cross-platform karaoke player