Garbage Collector Spy Tool
Introduction
The Garbage Collector Spy Tool, or GCspy for short, is a generic and highly-adaptable heap visualisation framework, designed to visualise a wide range of memory management systems, whether they depend on garbage collection or implement explicit de-allocation. For a more detailed explanation of GCspy, have a look here.
Download
GCspy is freely available under an open source BSD-style license from here.