If you are comfortable with the command line (which I assume you are since you have a linux box) there are lots of command line tools that will run on linux or OS X to do mass tagging. Do a search or sourceforge.net for id3. I do initial tagging with iTunes and clean up/mass tagging with a perl script I wrote a while back. For me it is usually faster to do this kind of stuff with a good command line tool and a web browser pointed at allmusic.com than with a GUI tool.

-Mike