Cheap / free

  • ThinkDetroit weblog has a post about two ways; set up a small horseshoe rink!
  • Plant sunflowers

Moderate

  • Kent U's LandLab has published a series of books & booklets detailing some land-reclamation projects, including expected costs.
  • Hang up a sheet, find a projector and speakers, and play movies for your neighbors!
  • Install a picket fence; it will discourage dumping and look better
  • Make a mini-library and recruit volunteer librarians
  • You can start an urban garden.

Expensive

Big revitalization plans that take lots of money

Creative