I still have a good number of songs in my music collection that have poor or missing ID3 tages. I thought that, with 2008 nearing and all, perhaps somebody had finally made some progress on a tool for automatically fixing this stuff up. I tried iEatBrainz and MusicBrainz Picard and didn’t get very far with either one. I also found id3tool which is a very handy command line utility, for those who are familiar with sed, awk, and the like.
I learned about id3tool from this page. It includes some nice example shell scripts and points out that you need to select the songs you modified and choose “Get Info” to force iTunes to re-scan the ID3 tags of the selected songs.