ESRI has a new, interactive tool which allows you to compare NASA LandSat imagery, anywhere in the world, from two different dates
Satellite imagery is available at 5 year intervals from 1975 to 2005, and includes five visualization options – Natural color, Healthy vegetation, Infrared, Land/Water boundrary and Vegetation analysis. Maps from the two selected dates are shown side by side. A third panel, created on-the-fly, highlights vegetation diferences between the two.
Check out the Changematters viewer here.