many years ago I wanted to do the same, a socialized browser. At the time I was a heavy user of google reader that had a social reading list like what you described. I imagined that the social reading experience can be integrated into a browser.

But I found out (on google reader) that my physical friends have drastically different interests from mine. They have no interests in my shares and one friend even complained that I spammed her. And actually, most of my friends don't read.

Eventually I didn’t work on this idea. I felt that it won’t be too much different from sharing on Twitter. I still have my UI mock-up for the project though.

https://images-wixmp-ed30a86b8c4ca887773594c2.wixmp.com/f/87...