Amazon Best Seller List

For the first time in like a month, the iPod Shuffle rose to the top of the Amazon best seller list for electronics. The last several weeks it has hovered around number 21, and today (this morning) it's on top! I find it so interesting to watch online shopping preferences fluctuate. In fact, right now the MP3 players are totally dominating electronics, whereas the last few weeks a couple oc camera models have been going crazy! Why is the shuffle on top right now and not before? Any theories?