The academic world could benefit from a place that allows commenting on any paper (you can have too many comments; not sure how moderating such a system would w

The academic world could benefit from a place that allows commenting on any paper (you can have too many comments; not sure how moderating such a system would work). To this end, it would be great if this were written in such a way that it implicitly considers papers from all the "standard" academic sources as part of the system, ideally with duplicate removal. That is, automatically add articles from arXiv and major currently existing journals and conferences, try to automatically detect duplicate papers (perhaps add a concept of versions of papers). In addition, such a site could really benefit by having "virtual journals", where users collect topical collections of must-read papers.