Abyssmedia BPM seems really cool. It's easy to navigate and it has very accurate readings of BPM; however, it doesn't save any of the BPM information to the file. Once it's done analyzing, you have to manually input the BPM info into iTunes. And, it only does one folder at a time. Since iTunes gives every artist and album a different folder, you have to individually select each and every folder to see what the BPM are for the songs inside that folder.
I was excited at first, but it fell flat. And there is no included manual or much of a help-site, so if I'm doing it wrong, there's no way for me to learn how to do it right.
With MixMeister it seems possible to import the BPM information, but I need to delete the current file out of my iTunes program (not remove the file from my computer, just delete the reference to it in my iTunes) and then drag and drop it from MixMeister--it's possible to do, but it's really labor intensive. I'm not a fan.