I'm looking for some middleware that handles adding a "comment" system on to arbitrary pages in a webapp, that allows the user to use their Facebook or Twitter (or perhaps Google and other similar systems) to leave the comment.
This sort of functionality exists as plugins for all sorts of web apps (socialee for ExpressionEngine, various plugins for WordPress) but I'm looking for a system that can be used anywhere.
The closest example would be Facebook's Comments Box plugin but of course that only works for Facebook accounts. I want to give the user more freedom to use other accounts.
I think you are looking for http://disqus.com/