[jjm]

Take a look at this: http://www.percona.com/software/percona-server/for-nosql/

There is one for mysql: https://github.com/ahiguti/HandlerSocket-Plugin-for-MySQL

But i would urge to go with XtraDB.

I use mongo for everything but the money (where cash is not involved) and for things not needing transactions. Have been sticking to MySQL for everything else (now moving to XtraDB).

For big big big projects and pure nosql I go with Cassandra (as long as you can feed it enough RAM). Otherwise, XtraDB can go the distance.