I've been working on this solution and am currently in a closed beta. Will be opening up this/next week over time. http://hivereader.com I meet all your requirements but the cross platform. Once the web API's are locked (aka near the 1st) I am going to start cranking on the mobile app ASAP as well as a public facing api. I also have social but you don't need to use it. (no really, it's barely there).