Interesting Sites.

Counterfeit British Coppers
A facinating series of articles from the University of Notre Dame.

'copperclem'
Clement V. Schettino's website. Lots of images of counterfeit halfpennies and a few farthings. Some of them are fantastic!

Values of coins
This price guide at Tony Clayton's excellent British coin site is an invaluable resource.

Lloyd Roberts
Lloyd has a lot of British coins for sale, including some very rare items. Well worth a visit.