PakistanSurvey.org is using MongoDB for general data storage of tons of survey responses and aggregation of them. Similar sites we're working on use CouchDB in

PakistanSurvey.org is using MongoDB for general data storage of tons of survey responses and aggregation of them. Similar sites we're working on use CouchDB in the same capacity, because we can push simple analysis back into the database and represent more complex data in a natural form.