Back in 2001, I was working on a web based EMR system.  We had a problem of displaying terminology that happened to be very hieratical.  This is very similar to the start menu in windows or the file explorer.  The problem was to present this intuitively on a small mobile tablet device.  Although, I didn’t end up using it, I found this:

http://www.thinkmap.com/architecture.jsp based on research done at Xerox Park (http://en.wikipedia.org/wiki/Xerox_PARC). 

This would be cool done in flash or silverlight technology.  I think it would be interesting to apply this to a family tree application.