Cool slide show. The Landsat Imagery | ChangeMatters Viewer is works great for seeing how river's change over time. These are shots of the Arkansas River where it dumps into the Mississippi. The changes occurring there are fairly rapid.
To collect other photos maybe you can search in the USGS landsat 5 database or search in the VMAP0/ VMAP1 data World database. As far i know this vector data is not very bad, especially in the USA.
