For a while until around August 2009, I did a lens based on the New York Times best seller lists, updated weekly. After not seeing sales for many months, I deleted the lens since it took about 2-3 hours every week to update it.
When I resumed activity around Thanksgiving 2010, I realized I'd made a serious coding error that prevented sales with affiliate links from being credited to my account. Now I'm going to try again, this time with correct coding. I had been getting some sales until I started using the bad code.
Instead of using the hardcover list, I'm using a new list the Times started earlier this month that reports combined print and ebook sales. Since ebook sales at Amazon.com are now larger than hardcover or paperback sales, this appears to be the best way to reflect what people are actually buying.
Alone is #2 on the latest New York Times list of print and ebook fiction best sellers.