Goggles Music Manager is a music collection manager and player that automatically categorizes Ogg Vorbis, FLAC, MP3, MP4, ASF, and Musepack files based on genre, artist, album, and song. It supports gapless playback, features easy tag editing, and allows scrobbling tracks to last-fm.
Flac2All is a multi-threaded script that will convert your collection of FLAC files into either Ogg Vorbis, MP3 (with the Lame encoder), or FLAC, complete with any tags and identical file/folder structure. The script has been stable for about a year now, and it has been known to saturate 8-core machines with parallel conversions. It is useful for people with with large FLAC collections who also want a lossy version for portable media players. If wanted, the script can perform updates by skipping already converted files. It has only been tested on Linux, but it should work without alteration on the other Unix systems with bash and the required dependencies.
puddletag is a tag editor for Linux loosely based on mp3tag. It uses a table layout so that all the tags you want to edit by hand are visible and easily editable. puddletag excels at automating repetitive tasks like extracting tag information from filenames, tagging files from a text file or the clipboard, renaming or moving files and folders based on tags by using patterns, and manipulating tags using actions and regular expressions. Supported formats include id3v1, id3v2 (.mp3), AAC (.m4a), VorbisComments (.ogg, .flac), and APEv2 (.ape). Much of mp3tag's functionality has been replicated with added enhancements and tweaks.