Profile recommendations - what is it?

We plan to broadcast user recommendations on the following categories of sites: blogs, media, social networks.

What is it for?
Firstly, to collect statistics. Secondly, we are interested in building a rating of user preferences. Probably, many will be interested to know which blogs and media are most often read by users of this site, which networks they are members of, and so on.

We plan to ask for recommendations on three categories of sites (blogs, media, social networks), but the list can be expanded, suggest :-)