I am working on this too..
I took George’s Ringer code (http://www.magentocommerce.com/boards/viewthread/3999/P15/) which displays category best sellers and am working on a way to make it show store wide bestsellers when I add it only to my home page (via xml update for home page).
Currently it isn’t showing due to the fact that the home page is no category (just a cms page) and has no (best selling) products .
I’ll try to update this thread with my experiences.
Inchoo.net has a great tutorial on how to get this feature working. This tutorial can be found at: