JavaShark
Sniffer and knowledge sharing tool for java platform
JavaShark is a new way to view/trace/analyze JVM applications. It's like an advanced debugger with Groovy support. And the most important - now you can share your knowledge about any system with people around the world - just share your handlers(breakpoints) bundle. Just imagine - you connect to the remote JVM, attach handlers bundle and now you know much more than any logs could ever give you. It's free and open source under MIT license.