Google Art Project od Jeremy Schomery

Art Project For Firefox is a simplified version of Google Art Project extension for Google Chrome browser. It displays Art Project masterpieces from Google Cultural Institute in your Firefox's new tabs.

Quoted from Google Chrome extension:

With this extension, in every new Firefox tab you'll see masterpieces ranging from Van Gogh and Monet, all the way to contemporary works from street artists around the world. The artwork is refreshed every day.
If an artwork happens to spark your curiosity, click the image description to discover more on the Google Cultural Institute website.