Jul 26, 2007 at 8:42 PM
"SpatialReference website lists projections information in various formats. In addition to seeing existing EPSG codes, users can submit their own projections. Information for projections are translated in GML, Proj4, ESRI WKT, OGC WKT, USGS and JSON. Comments about the projections can also be shared." (Via slashgeo

I found remarkable its RESTful qualities. I miss a XML or JSON list of all available references ;-)

Best regards,
Ricardo Stuven.