From November 19th, 2013 to November 19th, 2013, 100% user give 5-star rating. for PageChat Beta chrome extension.
Years ago, there was an application that would let you annotate any page and view other annotations left by other users. Unfortunately, its use was mostly for graffiti. A chat-based approach is much more sensible. Seems good so far. A little font tweaking would go a long way (even just a switch to anything sans-serif would help).