From the webpage:
PubMed Commons is a system that enables researchers to share their opinions about scientific publications. Researchers can comment on any publication indexed by PubMed, and read the comments of others. PubMed Commons is a forum for open and constructive criticism and discussion of scientific issues. It will thrive with high quality interchange from the scientific community. PubMed Commons is currently in a closed pilot testing phase, which means that only invited participants can add and view comments in PubMed.
Just in case you are looking for a place to practice your data skepticism skills.
In closed beta now but when it opens up…, pick an article in a field that interests you or at random.
Just my suggestion but try to do very high quality comments and check with others on your analysis.
A record of to the point, non-shrill, substantive comments might be a nice addition to your data skeptic resume. (Under papers re-written/retracted.)