Currently, there isn't a complete web-based solution for this requirement, but ServiceMix does have a few extension points which allow you to easily build this yourself.
There's is an ExchangeListener interface available -- this allows you to plug in straight in the heart of the NMR itself, automatically receiving callbacks for every single message that passes through the ESB. This should allow you to store just that information about the MessageExchange that you are actually interested in so you are able to visualize that afterwards.
We used this ourselves to provide you with a JDBC- and File-based ExchangeListener implementation -- messages are archives either in a RDBMS or in the filesystem. These classes are called JdbcAuditor and FileAuditor and will be available through JMX for remote management once you configure them (i.e. add them to conf/servicemix.xml). If you want this for your own implementation as well, just extend AbstractAuditor (which also implements ExchangeListener).
By the way, it has nothing to do with message tracking, but if you also want to monitor how/if the ESB is running, you can install FUSE HQ to do that.