[mathgenius]

So far it seems that scirate is used just for the "like" button, which is the one big missing feature of the arxiv. (And probably should not be implemented there anyway.) Most science trolling still seems to happen in a very public & attributed way, via those articles with title "A note on..."

[tvawnz]

I'm not sure how it is in other fields, but in Astronomy we have a monolithic database of publications (called ADS) where you can search by author or title or date or keywords etc. And there are sort options for views, downloads, citations, etc (all with time data, so you can see trending behaviors). IMO that serves the same function as "Like" but better.