Cardio is a library that can play back many different audio files (MP3, FLAC, WV, MOD, etc.). It handles both the input (reading files) and output (writing audio). Cardio is extensible via plugins, many of which are available at the Cardio Web site.
BackToBasics is a simple music player for Linux.
A unit converter and calculator.
A flexible one time password authentication system with pluggable OTP algorithms and userstorages.