dudl is a collection of tools to grab, encode, and rename MP3 files, archive them, and maintain a database of all files. On top of this runs the dudld Jukebox daemon that plays your files through gstreamer. dudld's strengths are the powerful tag based filters, the capability to cope with very large collections, and the network protocol to control its operation. There is a full featured command-line client, a minimalistic GTK client, and a lirc client. Writing new clients should be easy with the supplied client libraries.
Neformal is a small audio player with a file manager and the ability to play file by file. It can keep bookmarks for favorite directories. It can compute RMS statistics for 16 bit PCM WAVs. Song lyrics are supported (via lyricwiki.org). Drag and drop can be used to interact with other applications. ID3v1 and ID3v2 tags are handled flexibly. The charset for tags can be selected. There is a built-in viewer for images and text files. The output device can be selected.