The ad above was created by Jenny Burrows and Matt Kappler for their art portfolios. Originally, the logo at the bottom belonged to The Smithsonian. But once Jenny and Matt's work started getting attention online, the Smithsonian folks decided they weren't crazy about the free publicity and asked the artists to take down the ads immediately. Jenny ended up swapping in the generic "Museums" logo seen above.
If you like the Roosevelt/50 Cent ad, be sure to take a quick trip over to Geekosystem to check out more of the wonderful posters.