I too am interested in this concept as well. I'm looking for the ability of members to 'Digg' content for lack of a better term. Once they add an article as their favorite, their member image and name would show under the article. It would be nice to see in the CB tab which articles they favored as well. Does anyone know if there is any exisiting functionality like this for CB? If not, I may head over to Joomlancer and see if it can be created.
Bookmarks - component with a lot of features. Maybe more that we want for this application. No CB plugin that I know of.
JPortfolio - "This is a portfolio (showcase) component, where you can show multiple samples of your work, in different categories." Don't know if it will showcase your favorite links from within the website.
jh_Favorites - Maybe the closest: "..creates a list of favorites for users with checking to make sure the same user doesn't add the same article teice. ... The module creates a list of 'x' favorites (definable through parameters) and a link to view all of their favorites."
Akocomment has a favorites system that does exactly what your looking for. The only problem is that it does it without integration with community builder and also there doesn't seem to be a way to shut off the comment part of akocomment. So maybe the favorites code in this component could be used to quickly create a simple plugin for community builder that stores favorites and an accompanying mambot.
I will look into developing something in this regards.