Next Generation lists The top 100 selling games of the last 12 months. They promise to publish a detailed look of the selling data tomorrow (also the older list with some descriptive statistics is available).
I am not sure if the sales list is usable for anything, but I decided to make a note of this if I would like to site or take a deeper look on the best selling titles later on.
Update (12.4.): Best selling games — the analysis is available.
Petri Lankoski 