I have recently discovered a website, PubPeer (via @grolimur). It allows to comment on scientific articles. Their goal is to "create an online community that uses the publication of scientific results as an opening for fruitful discussion among scientists". And there is an addon to directly see the comments on the journal websites.
I have just tested it and I was looking for an article not in my field. Google Scholar recommended me a conference paper / preprint, available on of the authors website, "Content Diffusion in Wireless MANETs: the Impact of Mobility and Demand". This is typically the article you would like to comment: recent research, not published yet, where your comment would impact the most. Unfortunately, it is not available on PubPeer.
Google is smart enough to collect it, but not (yet?) PubPeer.
Now I am frustrated, so here is the comment I would do on the paper if it was available:
In your paper, you show how how time of day, day of the week and site impact the diffusion potential when wirelessly sharing content via Mobile Ad hoc NETworks (MANETs). "The potential efficacy of multi-hop MANET content diffusion is heavily influenced by small-scale patterns of mobility and content demand", your write. "The rate at which content spreads throughout a network is highly site-dependent.
I am not an expert in your field, but it might be useful to add "activity" in the list. People don't have the same usage of the internet if they are eating or studying on a campus. You mention that your problem is "highly site-dependent". Maybe it is more than that: it is activity-dependent, and there is a strong link between the location and the activity (if you're in the restaurant, you're probably eating). "Activity" might not be so different than "day of week" + "time of day" + "site", but still, it adds information.
I am a little bit biased: I recently published a paper about how to infer activity type based on WiFi traces, land use data (pedestrian network and a measure of attractivity) and time of day (if you cannot access the article, postprint available here).