"Coexist" logo was created by a Polish artist Piotr Młodożeniec. A short history of the logo is here: (mostly in polish)
The logo was designed for a competition in Jerusalem's Old City. Links to other proposals:
"Coexist" logo was popularized by U2 & Bono
Coexistence is on minds of other people too:
Some people make money on this, below are two bumper-stickers for sale:
(links are not provided, find them yourself, there are also fashion lines attached to this logo)
Good ideas find many enthusiasts, perhaps there will be more variations of Młodożeniec' logo, one example is here:
