Graph API / framework

[George Sakkis]

Does anyone know of a good graph API ? The only one I found for Python is
part of kjbuckets
(http://starship.python.net/crew/aaron_watters/kjbuckets/kjbuckets.html),
but I was looking for something more sophisticated; I am more concerned
about elegance and extensibility than top performance. JUNG
(http://jung.sourceforge.net/doc/manual.html) for java looks more promising.
Does anyone have experience with it or some other relevant framework ?
Thanks,

George