looking for a combination contact application/social networking app

hi... i'm in need of a glorified contact type application. i want/need to be able to allow users to enter their information into the system, specify what category(s) they belong to, be able to see others, rank others, etc... i also would like to be able to have some form of relational/6-degrees/ryze type of system so the users can see/find others with similar interests.. and of course, i'd like this to be open source!!! anbody have any ideas, or seen anything closely resembling anything like this.. i'd even be willing to look at multiple apps, with the intent of putting them together as a comprehensive app!! thanks bruce bedouglas@earthlink.net