Command-line utility that wraps multiple MP3 files into a single, playable MP3, without losing filenames or ID3 information, and without reencoding. Also supports archiving non-audio data such as playlists, info files, and cover images inside the MP3. These files can be unpacked later (using mp3splt, e.g.); ordinary MP3 decoders can play the entire audio stream as one long track.

This is a free, independent alternative to AlbumWrap: http://www.infamus.com/albumwrap/