I dont know if there are many people here on similar issues, but this is a HUGE area. Subscribe, first of all to the AoIR mailing list, its the association of internet researchers mailing list. next i suggest go on to google scholar and locate the key readings, if u have access to elecytonic journals great. Its a huge area with researh being contributed from media and comm, information systems and so on but mainly these. For one instance, there is a ton of research on anonymity and trust and privacy on social networking sites, search with these terms on google scholar and u shall find plenty. As a great place to start with a list search for danah boyd on google, go to her website, i think its called apophenia.org and she has a list of research on thse sites, in which you shall find some starters on anonymity, trust and privacy and then from the bibliographies of those pievces you can move on further.
good luck!