Some readings:

http://www.sun.com/bigadmin/content/submitted/cms_gc_logs.html
http://java.sun.com/docs/hotspot/gc5.0/gc_tuning_5.html
http://java.sun.com/docs/hotspot/gc1.4.2/example.html
http://blogs.sun.com/jonthecollector/entry/when_the_sum_of_the

http://java.sun.com/j2se/1.5.0/docs/guide/vm/gc-ergonomics.html
http://performance.netbeans.org/howto/jvmswitches/index.html
http://java.sun.com/javase/6/docs/technotes/guides/vm/cms-6.html

http://java.sun.com/performance/reference/whitepapers/tuning.html
http://blogs.sun.com/watt/resource/jvm-options-list.html