Thanks to those who responded to my question about SNA software. Here are the packages that have come to my attention so far:
Not a whole lot out there for this kind of application. InFlow seems to be the most well known based on inquiries I’ve made.
C. David Gammel, CAE 
Are you talking about FOAF-type information? Here’s one – http://jibbering.com/foaf/
FOAF = friend-of-a-friend. This is an experiment in using RDF to depict who-knows-who – and there’s been a lot of discussion of using it in “trust networks” – that is, if I know Sue and Sue knows Ted, then I have a higher level of trust toward Sue than Ted. Also more trust toward Ted than toward someone with more degrees of separation from me.