I think it's an interesting idea. I track about 200 feeds, but probably look at only a small percentage of the stories. I definitely would appreciate help in blocking out the least interesting stories.<p>That said, limiting the free account to only 3 feeds makes it difficult to judge the site's usefulness. I guess that I would probably want to try the site out with at least 50 feeds to see if I wanted to pay for the ability to track even more feeds.<p>Consider that it may be more valuable to give out fewer invitations but raise with numbers of free feeds per user.