OpenStreetMap Points of Interest Database
Synopsis
Not sure if this is a common method for geospatial databases or not, this stores nodes and keys by their average coordinate encoded as GeoHash for query by location.
Importing an OSM Protocol Buffers Dump
I recommend pipeview for monitoring progress:
pv -per < region-latest.osm.pbf | node osm2leveldb.js
Query
By latitude/longitude + maximum extend:
var AreaStream = ; lat: 51 lon: 13 extent: 5000;