I just did a whole bunch of id3 tag editing last night.

After trying a few commandline tools, i found tagtool which is a lightweight GUI program.

It does individual file editing, group editing (including auto incrementing track numbering).

It can tag the files based on filename, and it can rename the files based on tag. Renaming a file can also be used to move the files into directory structures based on the tags.

and it does playlist generation.

Compared with other taggers, the file rename and auto track numbering were the big timesavers for me. (I've changed my mind about file naming schemes many times when ripping my CDs over the years.)