A very good general overview of the Theory of Plate Tectonics and its historical development from the United States Geological Survey. (
http://pubs.usgs.gov/publications/text/dynamic.html
)
NASA wewbsite describing a precise, space-based method for determining plate motions across the Earth. (
http://cddisa.gsfc.nasa.gov/926/slrtecto.html
)
A series of maps and globe views of Earth during different intervals of geologic time. The maps are based on reconstructions of continental positions using principles of Plate Tectonics. (
http://vishnu.glg.nau.edu/rcb/globaltext.html
)
If you don't like the other map products on this list, here's a website where you can make your own! Enter a time interval of Earth's history, choose your projection, customize some other features, and GO! (
http://www.odsn.de/odsn/services/paleomap/paleomap.html
)
A computer program to calculate rates of plate motions provided by the Ocean Floor Geotectonics Research Group at the University of Tokyo. (
http://triton.ori.u-tokyo.ac.jp/~intridge/pmc/plate_motion.html
)