After seeing MusicBrainz pop up on my del.icio.us popular page, I went and checked it out. I tried using it on my barrel of MP3’s that I had no hope of ever fully classifying, or really figuring out where they came from. I was shocked, not only at how well the program worked, but how easy it was to use. It even respects how I name files, and will handle that for me as well!
I still use Tag & Rename to finish up with assigning a year, and getting the directory structure exactly how I like it, but MusicBrainz has already become an indespensible part of my MP3 stack.
In short, if you have a lot of MP3’s, or you are an active downloader, please use a condom.
Wait! No, I mean, give MusicBrainz a try.