You can see the Top 100 Free (and Paid)
here, you can subscribe to the Top 10 as RSS Feed as well.
It's funny though, that Amazon's link to this list, as well as NYTimes Beststellers, Editor's Picks etc. are only visible (within the left navigation bar in the kindle store) if you set your region to "United States", "Europe" doesn't work.
BTW, there are also links to "language lists"
Spanish,
French,
German,
Italian and
Portuguese