Amsterdam's home of some of the greatest paintings of the Dutch Baroque has what it calls the "Rijkswidget": it allows Mac and PC users to see a different painting from the collection each day.
Nifty . . .
or it would be if, that is, my computer and the museum were on speaking terms--which they aren't, at the moment.
Correction: It's working now, and the first image is this one, Rembrandt's The Prophetess Anna.