Malene Charlotte Laren, a PhD student at Aalborg University in Denmark, has defined 35 different perspectives for evaluating social networks. I don't know how groundbreaking her work is, but I thought it warranted at least a mention on this list. Article here: http://www.socialcomputingmagazine.com/viewcolumn.cfm?colid=432 Malene's blog here: http://malenel.wordpress.com/ -Conor