The first computer simulations of the giant impact theory are due to:
The following links illustrate the more recent work of Robin Canup
William Hartmann's descriptions of some of his paintings:
This link provides a superb introduction to plate tectonics.
This link to mantleplumes.org provides extensive discussion of the latest theories about plumes, hotspots and plate tectonics. There is a lot of controversy in this area.
An Alternative Earth is a technical account of current thinking on plate tectonics.
This link provides a good introduction to geomagnetism.