GeologyRocksuk
Interactive Geology Map Of The UK - http://www.bgs.ac.uk/education/makeamap/flashfile/makeamap_2005_html.swf
The BGS has an interactive map of the Geology of the UK (Flash / Shockwave required). Outcrop distribution for different geological periods can be switched on or off and mousing over the information button for a period brings up a timescale for that period. Very useful for teaching stratigraphy.
[Hat-tip: Highly Allocthonous Blog]
A lottery-funded website detailing the geological history of the English county of Shropshire. There are detailed descriptions of various rock types found in the area, along with an animated character who will help you identify your "pet rock". Worth a look around, especially if you're planning to visit the area.
