(Based on cumulative sales from Artcyclopedia.com)
The most popular artist searches last month: a not-to-be-taken-too-seriously measurement of which famous artists have the greatest "mindshare" in our collective culture.
Moving up: Most notably, Georgia O'Keeffe (#10 to #7) and Alfred Stieglitz (#81 way up to #11) -- presumably due to the Lifetime Channel's TV movie Georgia O'Keeffe, starring Joan Allen and Jeremy Irons. I didn't get to watch the movie, but it has a superb cast.
Moving down:Rubens (#6 to #12), Titian (#16 to #26) and Pieter Brueghel (#18 down to #38).
How we measure popularity: In order to eliminate any kind of selection bias due to search engine ranking, external links, etc., we only count internal links from our own search box and our artist listings.