Java garbage collection analyzer

IBM Pattern Modeling and Analysis Tool for Java Garbage Collector is "a tool that parses verbose GC trace, analyzes Java heap usage, and recommends key configurations based on pattern modeling of Java heap usage".

I remember I heard about a similar tool for HP JVM on HP-UX (I think Kirk Pepperdine told me about it on the train from Aarhus to Copenhagen this October when we were travelling home from JAOO) - it'd collect GC statistics and then provide you with a GUI where you could play with sliders for various memory settings, and it'd calculate how would have the GC behaved if the program was run with those settings.

On a somewhat related note, as someone who had to do some ammount of GC tuning in the past, I'll be curious about experiences people have with Java 6's GC that is said to behave optimally in most situations without any manual tuning... It sounds enthusiastic, but I'm too often reminded that in reality there is no silver bullet in automatic memory management.