The Next Generation of New Urbanists (yes, these are young New Urbanists, because New Urbanism has been around long enough that it's getting a little ... old) and the Street Plans Collaborative want to help. They've put together a "Tactical Urbanism" guide that you can download for use when you need some ideas about how to catalyze lasting change in your urban world.

Examples include guerrilla gardening, pop-up cafés, mobile vendors, and "Build a Better Block" projects. Most involve partnership with government agencies or local business owners, but they are almost all things that ordinary folks can initiate

http://www.grist.org/urbanism/tactical-urbanism-guide-for-guerrilla-urbanists