A part JBoss Operation Networking / RHQ not to my knowledge.
I dont know about anything either, but contributions are welcome :-)
Well mod_cluster uses Apache httpd so you could use those tools to monitor it. Here are two I have used:
There are plenty of other log analyzer tools out there for apache.
Also if you have a separate host for Apache you could use a system monitoring tool like nmon for monitoring throughput, CPU utilization and such.
Thanks for the details!
Do we have similar utility like JKManager to control the traffic dynamically? For example, stop traffic going to specific node
There isn't a JKManager but the mod_cluster-manager page allows to enter commands to stop a node, it is quite easy to write a client to sned the commands.