Personally, I use the id3tag command line tagger from id3lib, and then run it from inside a Python script (attached), which does regex matching on my filenames to figure out which tags to use.

Check out http://www.id3.org/implement.html for alternative implementations if you feel like hacking something together in your favourite programming language.

Note that I couldn't get id3lib -pre2 to compile, so I used -pre1 instead.