Graphviz only renders a graph which is represented as per dot format. There are other programs: dot, neato etc which can produce jpeg,png,gif... formats through command line tools.

I guess what he meant was tools which can do this for a particular site.

I can't think of any but as a previous poster said - a crawl of desired depth for all local pages, then feed the access log to "statviz" to generate a neat dot file along with the links.