It would be good, to have the POJO Mapper Morphium listed on the Java Language Center as an additional 3rd Party mapper.
Dispite some of the other projects listet there, morphium ist actively developed and in productional use at some large installations (one of which is http://de.holidayinsider.com).
It also supports:
most important: simple POJO Mappings.
Declarative Caching, Polymorphism, simple and complex queries, is cluster aware (e.g. synchronize application caches), callbacks for lifecycle and profiling and includes a messaging system which uses Mongodb as backend...

A list of all the features can be seen here: http://sboesebeck.github.io/morphium/

thanks