Last week the Obama Administration announced its Open Data Policy, which requires federal agencies and departments to make their data available in machine readable formats and is meant to make government more open and accessible through technology. A number of federal agencies have already made their data available in this way, and 39 states and 35 cities and counties have begun to make government data available through open data web sites. They allow us to answer questions such as: Where have building permits been issued in Washington, D.C.?; Which restaurants in Boston are violating health codes?; Where are traffic cameras located in Honolulu?