I use a tool called zotero for collecting research references. It is a browser plug-in which can be used to “bookmark” and annotate web-sites for academic purposes. There is only a “fully developed” version for firefox.
I recall that google side-wiki had a similar premise, which was to provide annotations to web-sites and provided plugins for internet explorer and google chrome. I think it would make any interesting base, or reference for developer an internet explorer version of the plug-in.
The links that I can find to google side wiki all go to “this project is deprecated”.
Did google release the source code to the browser plugin parts of sidewiki? is that still available in some archive somewhere?
Unfortunately Google Sidewiki is not available as open source. There have been some open-source web annotations systems but I’m not sure if any of them will fit your needs. There’s a reasonably good list of them on Wikipedia: http://en.wikipedia.org/wiki/Web_annotation