VisualVM Preview 1 has just been released at https://visualvm.dev.java.net. VisualVM is a visual tool that integrates several existing JDK software tools and lightweight memory and CPU profiling capabilities. This tool is designed for both production and development time use and further enhances the capability of monitoring and performance analysis for the Java SE platform. Actual version of the tool works with JDK 1.6 but is able to provide some data also for older JDKs.
As you can see at the screenshots below, VisualVM shows you all JVMs running on local system, it's also able to monitor JVMs running on remote hosts. For each running Java application an overview is displayed (PID, JVM version, arguments, system properties etc.) as well as basic telemetry data (threads, memory consumption, classes etc.).
For each Java application running on JDK 6.0 and above you can create a thread dump or heap dump with just one mouse click and display it in internal viewer/heap walker. You can also do a basic profiling with an integrated profiler.