A Graph Drawing tool. http://www.touchgraph.com/
Uses its own "TouchGraph XML" file format, rather than GML.
Used on the MemesNet site. (Though that doesn't seem to work lately.)
Built by Alex Shapiro.
Built in Java.
Seems to have become a commercial enterprise.
But there's still an Open Source project at Source Forge. But the code hasn't been touched since 2002!
There's a PubMed browser, though I haven't gotten it to work.
John Mc Dowall [is](http://www.mcdowall.com/Graph Layout.html) using it to map WebLog relationships.
Cool WikiGraph Browser.