Along with PubMed Commons comments, Lazy Scholar now also checks for PubPeer comments in version 0.8.1. PubPeer provides another option for critical discussion of papers.

Here is an example of a paper that has comments:





Clicking the link will bring you to the PubPeer page to read them. Similar to PubMed comments, if none exist, no text will show.

Thanks to PubPeer for API access. They also have a much lighter weight Chrome Extension that checks for comments as you are surfing PubMed pages, if that suits you better.