You can use xmms as a tag editor. (Though not terminal based, it does have a user-interface, which may be what you want.)
I prefer to use id3v2. Admittedly, it is command-line, but once you try it for awhile, you will find that it is very powerful and easy.
Mp3wrap is great for combining short mp3s into a single, longer file. That reduces the need to edit tags for books on CD, etc.