As you may know already, Mustang's jmap utility can create heap dump from a live process or core dump. Also, hprof profiler can create heap dump with or without allocation site information.
Heap dumps are binary format files that contain snapshot of Java heap. Mustang's jhat (Java Heap Analysis Tool) tools can be used to view and analyze the Java heap dumps. jhat includes interesting features such as OQL - Object Query Language.
Kelly Ohair has created a java.net project (https://heap-snapshot.dev.java.net/) to specify new Java heap dump file format. Please participate in this project and give us your feedback and suggestions.