The Gaia-SINS federated project home-page. Just quickly bookmarked in case I need it - spatial data (GIS data) can be efficiently indexed and queried in SQLite with an extension. Since I am a declared fan of SQLite, this is quite interesting. And it is implemented as a dynamically loadable extension (of course, this only works if the SQLite you are using is also enabled for extensions - unfortunately this is often not the case, installation might require a recompilation of SQLite, but it's not that terrible).