Bitcoin Charts [1] keeps history for dozens of exchanges (which all float at slightly different values) and has a free API to let you request any period of inte

Bitcoin Charts [1] keeps history for dozens of exchanges (which all float at slightly different values) and has a free API to let you request any period of interest. Beyond just market price, I think you can get records of every individual trade. If nothing else, this whole bitcoin thing is a fascinating experiment! [1] http://bitcoincharts.com/charts/ http://bitcoincharts.com/charts/