Jolokia is a JMX-HTTP bridge giving an alternative to JSR-160 connectors. It is an agent based approach with support for many platforms. In addition to basic JMX operations it enhances JMX remoting with unique features like bulk requests and fine grained security policies.
jmxtrans is very powerful tool which uses easily generated JSON based configuration files and then outputs the data in whatever format you desire. It does this with a very efficient engine design that will scale to communicating with thousands of machines from a single jmxtrans instance.