Insideout Art Project (that seems to be global one). I don't know much about it, but you can check the link and see if your city is involved.
More information about the city project at this link: http://www.manchesternh.gov/website/LinkClick.aspx?fileticket=3OYuv5EDeqM%3d&tabid=3075
Anyway, this was an interesting project. A photographer (Ann Kelly, I believe) took lots of photos of people at the Peoplefest festival in the fall. Various artists and others helped her put up the photos all over the downtown area.
Last night Joe & I met with another group of artists and we are hoping to organize more fun downtown projects. Funding is always an issue, but we have a core group and lots of great ideas.