Freecoin
Freecoin is a fork of the original BitCoin client, developed by DYNDY
Description
From the project homepage: "Freecoin is born as a fork of bitcoin (on 18 May 2011) and its main goal is not that of preserving the Bitcoin currency or servicing its circulation, but that of continuing the development of P2P currency software as an educational experiment and a free reference implementation for further innovation.
Freecoin is not a currency, but a suite to create P2P currencies"