Have you ever found a really great article and want to know what others are saying about it? Do you ever feel like posting a comment about an article for others to see? Perhaps you just want to know what people are saying about your own published work? If these questions spark your interest then you might want to check out PubMed Commons and PubPeer.
PubMed Commons offers users the ability to view and post comments on publications in the PubMed database. It’s a space of scientific discourse and a forum for sharing opinions on a work. Any PubMed user can view the comments directly from the database but in order to post new comments, users must have a MyNCBI account and at least one authored work in PubMed. Their Getting Started page details the eligibility requirements.
PubPeer offers a different level of service when it comes to user comments. It acts as an online journal club of scholarly works. Users can search for articles by PMID, DOI, arXiv ID, keyword, author, etc. If a comment on the retrieved article exists, it will appear in the search results. Commenting on articles is also possible in PubPeer, although there is little restriction on who can contribute. See their How To page for details.