It would be nice to be able to plugin JMX monitoring into the Java driver. Mainly pool size (min, max, avg, etc.), detected error counts (for a period of time) and average query/request times.

This would probably require some sort of registration with the mbean server in the Mongo object.

Take a look at this for more info:

http://java.sun.com/docs/books/tutorial/jmx/mbeans/standard.html