Dynamic call graph treemaps

I'm trying to come up with new visualization techniques for analyzing code.  The static structure diagrams / UML diagrams are all well and fine, but I kind of want something that shows the relationship among objects resulting from the actual code execution.

So I'm looking at whether you can create a tree map, where the tree reflects the call hierarchy of the code with each method as a node, but then the size of each node in the tree map is proportional to the amount of time spent executing that method.  And maybe a very Tufte-esque graph inside each node could reflect consumption of resources (like memory) that were allocated / released during the execution.