Hypergraph - hyperbolic graph visualization

Hypergraph is an open source Java tool that can be use to render hyperbolic trees and also graphs. Currently it has three different kind of applications :

1. Sitemaps and other trees using standard hyperbolic tree techniques. As it's a simple Java applet, it can be easily be embedded in every website.
2. Showing the structure of topicmaps.
3. Showing the structure of a Wiki. It uses WikiRPCInterface to connect to a Wiki. In contrast to TouchGraphWikiBrowser, this is an applet and can directly access the Wiki without the additional step to create an input file.

Try existing applications starting here and these examples here.