(Links to sites that illustrate the position of continents and plates through time)
Geology-Plate Tectonics, University of California, Museum of Paleontology. This page contains several animations (of different scale and file size), which show the changing positions of continents and plates through time. Most of the animations run from 750 million years ago to the present. You can stop the animation at any point in time to see what the continents looked like at that point in Earth's history. Once stopped, you can also link to more information about the Earth at that time. A note, the smaller file sizes load faster and are perfectly suitable for most applications.
Paleomap Project, by Christopher Scotese. This site provides 19 maps of the World through geologic time from 650 million years ago to the recent, including 3 maps of projected plate positions in the future! The maps were produced by the Paleomap Project. Not only do these maps show the positions of plate boundaries, they include color codes for mountains, shallow seas, deep oceans, areas of high rain fall, deserts, and active plate boundaries at the time represented by each maps. Note the Carboniferous is equivalent to the Mississippian and Pennsylvanian for those more familiar with American systems and periods.
Global Earth History, Northern Arizona University, Flagstaff. This site uses a series of plate-tectonic reconstructions to show the broad patterns of Phanerozoic earth history. Included on this site are (1) 14 reconstructions of plate positions from 510 million years ago to the present projected on a globe, so that the reconstructions appear like the Earth from space, (2) 21 tri-part maps showing more detailed maps of the sedimentologic, tectonic, and paleogeographic evolution of the North Atlantic region (including North America), and (3) 28 maps that display major tectonic elements through time.
Webdogs, Department of Geological Sciences, University of Kentucky, Lexington. This site provides models of Pangean supercontinents that you can tear apart through time with your mouse from 150 million years ago to the present. You get to make the Atlantic Ocean!
Plate Movements and Climate Change lesson plan, Karen Bice, Pennsylvania State University, University Park. An on-line lesson for high school students and introductory college students, in which students gain an understanding of plate movements and how they may have affected the climates of the continents. The Paleogeographic Atlas of the World site, which is described above, makes a great follow up for this lesson.
For more about Plate Tectonics (some links with lesson plans)
To calculate the rate (speed) and direction of movement of any plate go to Plate Tectonic Motion Calculators