And it's not even good or recommended as a cache at any kind of profile. So I guess their most valuable niche is low traffic/prototype sites with poor architecture discipline or genuinely unrelated data sets. There are so much better tools for caching (memcached/redis), durable persistent storage (postgres), session storage (memcached/redis/browser hybrids) and document storage (postgres). Mongo is just one of those brands that quickly solved a problem that most of the better technologies missed - the user interface.