This is awesome.

This is a fantastically useful (and beautiful) mouse-interactive exploration of CSS blend modes and ways you can use them for artistic effects. I have to try redoing some of these using background layers on single elements.

A screenshot from the linked site.  It shows 16 copies of a detail from Hokusai’s woodblock print “The Great Wave off Kanagawa”, arranged into a 4x4 grid.  Each copy has a red vertical stripe covering a portion of its right side, but in each a different pixel blend mode is used to combine the red strip and the detail.