Citizens Against Ugly Street Spam (CAUSS) is a loosely organized group of people working to stem the tide of spammish signage that has become an epidemic in many cities and even some rural areas. Unlike e-mail spam, effective laws against signs placed within the government right of way are very common so removing them usually qualifies as picking up litter.
Citing declining property values, the Texas-based group claims to have removed hundreds of thousands of signs selling everything from Herbalife to loans to insurance since its inception in 1997.
Their website can be found at http://www.causs.org