"Likes", "comments" and "pokes" in scientific litterature?

I am a big user of Facebook. I use it to keep in touch, comment on stuff I am doing and...Oh come on, you're on FB too. But one thing that is also fun is to comment on what other people are up to. Maybe press "like" when someone has gotten married (congratulations Hanna!). Actually, I have gotten so used to being able to express myself in this blink of a second, that I sometimes wish other parts of my life was like this. For instance, in scientific literature.

When I read a paper and I see something is good, I wish I could press "like". Ok, I know this can sound a bit corny. But what if a doctor reads a report in a medical journal, and this helps her properly diagnose a patient, wouldn't it be a good idea for the doctor to express this opinion, without having to write a paper, and cite the work months later? Not everybody publishes a paper every day either. And lets say a second doctor saw the "like", and say "hmm, if this doctor likes this approach to treatment, maybe this could be worth a closer read to regarding my patient?"

Another thing that is appealing to me, is being able to comment on a paper online. Some journals already do this, like PLoS ONE (stay tuned for a paper by our group in this journal). This gives an opportunity to express one's opinion, although in this forum, the opinion is of course in a more scientific form. But it' s still more informal, and feels more dynamic. It could also potentially give the author the possibility to add quick corrections etc. before a more formal action is taken (i.e. submitting an erratum).
This can also be potentially used to quickly point out obvious wrongdoings by others. This can be especially important if your work, maybe life work, is under attack, without proper investigation or due to a misunderstanding (reviewers aren't perfect!). Submitting a letter to the journal, pointing out an obvious mistake, can take weeks/months, and the delay can potentially hurt your career for a long time! I was recently at a talk where the speaker felt the need to extensively defend his work from the conclusions of a weak paper (where is the "dislike" button?).

On the other hand, if you are the author of many papers, it would be impossible to address all comments made on your work, including unjust ones. But I guess this is the world we are heading towards anyway, as anyone can express their tired minds without revision or rejection, such as in a blog like this one.

I decided not to elaborate on how to poke a scientist.