Good luck. I wanted the same product when I was searching for newsletters and podcasts to subscribe to. I built a similar POC but never could find the hook that would get me to use the site daily/consistently. Commenting and social integration is an interesting way to get people to keep using the site.

I ended up with a fresh email inbox with 100s of newsletters and realized that it becomes a lot of junk. Only some of the daily articles are topically interesting to me and it becomes a game of subscribing and unsubscribing.

I think what I really want is to have individual articles rated and to only have those surface for me.

Another idea I had was to store every newsletter (which is usually just text and images) and then ppl can turn on a faucet to add/delete newsletters to their feed (fb style).