We are a group of Stanford students hoping to build a tool that measures third-party plug-in performance. A mocked-up prototype of the tool can be found at http://www.stanford.edu/~cliftonc/cgi-bin/
It's becoming more and more popular for publishers of prominent sites, such as Mashable and many media sites, to include third party web apps--for example, the Facebook "Like" button, or the Meebo Bar.
But it can often be difficult for publishers to tell how the third party code is effecting the performance of their site. Is the third party code slowing down their pages load time? Is it blocking the rendering of the page? Is it making too many asynchronous requests?
If anyone has any knowledge in this space--about what the pain points of a publisher using third party code are, about what features you would really like to see, or about what you like or dislike in this very early mockup, please let us know! We hope to build something useful for everyone.