I'm not sure how tuning the GC differes from performance tips and tricks, but maybe that's just me. I have seen some excellent info at IBM.COM as well. Sorry I don't have a link, but it was somewhere under WebSphere tuning; should hold true with or without WebSphere. I'm told the IBM JVM is close enough to Sun's that the advice should apply. I think every new release of the JVM changes the algorithms significantly, so be sure your references match your actual JVM.
A good question is never answered. It is not a bolt to be tightened into place but a seed to be planted and to bear more seed toward the hope of greening the landscape of the idea. John Ciardi