Via
disLEXia I found a link to the website of
fe3d. Its a visualisation tool for search results based on
nmap's port scans.
It should comile under Linux, IRIX, MacOS X and *shit*^WWIN32.
It doesn't only creates a 3d map of networks and their hosts, you are also able to change viewpoints.
It's definetly a nice toy but it could be also good for presentations and general visualisation of network infastructures.
Here is a little screenshot: