XFN Graph is an open source program by Geoff Holden for graph an XFN network out to four degrees. Java source is included.

Below is an example of my immediate network, click on it to expand the thumbnail.

Naturally there are missing links where people linked to colleagues but didn’t use XFN rel attributes.

I would like to experiment with modifying the program to use XFN where available, but to fall back on heuristics to identify other likely relationships links when XFN is not available. (For example, I might look for links containing first and last names based on a dictionary.)