There is a website dedicated to Photoshopping fun ideas: Worth1000
They run contests oriented around specific themes.
Todays is to incorporate a Robot into classic art works.
Some fun stuff, some hack work some excellent Photoshop-Fu Here is a thumbnail of one example:
You can view the full-size Photoshop here
The original can be viewed here William Bouguereau - Le Ravissement de Psyche