If the limitations of MongoDB's query facilities are getting you down, consider Couchbase. Couchbase supports JSON data natively, and has a very general query language called N1QL ("nickel"). If you know SQL, N1QL will seem very familiar.<p><a href="http://www.couchbase.com/n1ql" rel="nofollow">http://www.couchbase.com/n1ql</a><p>I'm on the N1QL dev team and would be happy to answer any questions about the language.