I just registered MPFreaker! And I have to say, great job! I have been using PC equivalents (such as TagandRename) - but I love how this is semi-automatic.
I do wish you had a way to get BPM automatically into the MP3s such as AsktheDJ software.
My only complaint is that b15 crashes a lot on my 17" PB OS X10.3.7. I have over 40,000 MP3s, and it took about a week to tag most of my music.
In terms of reporting, instead of the red error with the names of songs of an album all separated by album, it would be nice to have the error parse the songs in a list, line by line.