Potamus is a lightweight GTK+-based audio player with a simple interface and an emphasis on high audio quality. It tries to make it as easy as possible to use your file manager to locate and play music. Potamus can play a wide range of audio formats, works with ALSA, JACK,and other audio systems, and supports 24-bit audio and gapless playback.
Pogo is probably the simplest and fastest audio player for Linux. Its elementary-inspired design uses the screen-space very efficiently. Pogo is especially well-suited for people who organize their music by albums on the hard drive. The main interface components are a directory tree and a playlist that groups albums in an innovative way.
Impro-Visor is a music notation and playback tool for helping jazz musicians learn to improvise. It features a notation GUI, automated playback of chords and rhythm using MIDI, and improvisation advice provided in a variety of ways, including being able to improvise jazz itself. Data are stored as open-format text files. MIDI and MusicXML export are also available.
robonobo is social music sharing and downloading software. It allows you to share your friends' music libraries and playlists, stream the audio instantly, and download the file in the background so you can burn it, export it to your music player, or do whatever you want with it. You can import your friends list and share links to your playlists via Facebook and Twitter.
Flac-utils is a toolkit for managing FLAC files. Its primary usage is syncing metadata between sets of FLAC files. Flac-utils also provides a Python module called flac_compare that can be used separately. The utilitiy consist of three tools: flac-sync, which syncs a file tree of FLAC comments for files with the same audio-part; flac-diff, which compares two FLAC files' metadata information and shows the differences; and flac-add-picture, which adds album cover art to the files using Amazon.
Nextls is a console application that keeps track of your music collection using a MySQL database to store information such as length, bitrate, metadata, and where on the hard drive it is located. When Nextls is launched, it will figure out any changes done since the previous run and update the database accordingly. The database is very simple to work with, and there also exists a sister project in Nx2 that will allow you to take your database online and stream your music from a Web browser.
fretscpp is strongly inspired by the original FoF, reusing artwork to a large extent, with the source code rewritten from scratch. C++ instead of python should improve performance and allow easier support for features like whammy. It is playable, but some non-critical features are still missing.
CLAM chordata analyses the chords in a song and allows you to navigate along the song while watching several views to get insight of chords and other tonal features. Its simple and handy interface is designed for players with an instrument at hand. This application is part of the CLAM framework.