Yes, it's called python.

Write a crawler that examines all local links, and builds a graph (it needn't be anything fancy; a collection of nodes and edges is enough, but you'll have to detect cycles when building the graph), and then print it out in graphviz .dot language.

Then you can feed it into neato [either through a command-line pipe, or construct one using Python's subprocess module], et voilà, instant pagemap! :)

You can also use some of the rendering modes and scrape position data for the rendered nodes, if you want to generate a clickable imagemap.