Has anyone patched the code to experiment with the currency supply model?
There have been various experiments in this regard. The Alternate Cryptocurrnecies sub-forum is full of them. If I recall, Tenebrix and/or GeistGeld removed the halving block sizes, resulting in a coin without a cap on the number of coins.

Also, there is EnCoin, and alt whose price is supposed to be based on the cost of electricity.