Somehow, AMG managed to redesign AllMusic.com and make it even worse than before. They really don't want you to use their data (I've lost count of the number of times I've asked for an open API).
Anyway, now that AllMusic has officially disappeared up its own rectum, I recommend using MP3.com for music data. Here are two search bookmarklets: artist@mp3.com and album@mp3.com.