JavaScript: how to pass additional information to source page?

I have a website and when a user follows an internal link I would like to pass some extra information to a new page, so JavaScript on the destination page could do some useful highlighting.

There is an option to pass that information via the link parameters (GET), but it will generate lots of virtually duplicate pages and break pretty URLs concept. Another way is to make a webapp using AJAX, but it will also bound content to a single URL.

How can I transparently pass some information to the new page during navigation w/o messing with site's URL structure?