DeaDBeeF is an audio player for GNU/Linux and other UNIX-like systems. It is written in C with some plugins in C++. It has minimal dependencies, a native GTK2 GUI, cuesheet support, support for MP3, Ogg, FLAC, and APE, chiptune formats with subtunes, song-length databases, and more. It is very fast and lightweight, and extensible using plugins (DSP, GUI, output, input, etc.). The GUI looks similar to Foobar2000.
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.
Peyote is an audio player with a friendly MC-like interface. It is designed specifically to work easily with cue sheets. It plays wv (wavepack), WAV, FLAC, APE, Ogg, WMA, and MP3 formats. It supports ID3v2, APEv2, FLAC, and Vorbis tags; multiple playlists; and tabs. It can copy, move, remove, and rename files.