The mongo geospatial repository will be replacing several tables in the legacy mySQL system — as you may know, mongodb comes with full geospatial support so executing queries against a collection (table) built in this manner is shocking in terms of it’s response speeds — especially when you compare those speeds to the traditional mySQL algorithms for extracting geo-points based on distance ranges for lat/lon coordinates. The tl;dr for this paragraph is: no more hideous trigonometric mySQL queries!
http://architects.dzone.com/articles/challenges-mongodb-geospatial