Want to know a whole lot about the Earth's surface? NASA and the Japanese government are now giving away all the data from the ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) instrument... for free. Previously, you had to pay if you wanted anything more than basic topographical maps; now, you get over 16 years' worth of near-infrared elevation and thermal data. This is mostly helpful if you're a student or a scientist, but it could be worth a peek if you've wanted to see how everything from farms to volcanoes can affect the planet's surface heat.