Kind of new idea I'd like to introduce. If you know Google you probably have heard of the Page Rank which they use to express the importance of a certain webpage based on several different properties. This is where I started thinking from. There is also a ranking on technorati.com that tells you on which rank your blog is based on the links set to your blog from other blogs.
What I think might be existent in the future is a ranking for people. We see a lot of development in communities that have a certain social quality and display the connections of a person to other persons, organizations, companies, interests etc. You can see this in OpenBC, friendster, Passado, studivz. They all use the Friend-of-a-friend concept to connect people. However, I imagine a complex algorithm that calculates the unique importance of every person based on it's friends, interests, knowledge, intelligence, favourites etc. which would then be used to set up a ranking of the person. This is of course a gross idea.
I think people would provide the information because they already do that inside those communities I mentioned. In my imagined future those tools would be more elaborate hence the information-gathering shouldn't be a problem. This ranking could be used to find the best candidate for jobs and do other tasks of discrimination. I'm not sure at which point this could be interesting for the story but I believe it's a valid option to incorporate.