Bookmarklets as a means of creating active intermediaries by scripting and automating the browser.

Bookmarklets have been used for RSS Autodiscovery allowing subscription to a sites RSS feed to be made automatically.

I've recently produced a FOAF Autodiscovery bookmarklet by hacking Mark Pilgrims RSS version.

John Udell's Library Lookup project uses a bookmarklet that re-writes links containing ISSN or ISBN parameters into open OPAC links, allowing a user to check whether their library contains a journal or book.

There are also versions to go back the other way (reverse lookup) and even show availability inline (see also The Shifted Librarian).

Udell also produced another form of intermediary that generated a HTML form rather than redirecting the browser. See Please Acquire. This uses, as does the availability check, a "Bookmarklet Bootloader" that loads the real code from a server -- avoiding an IE limit on bookmark size. (As well as opening up some interesting possibilities with cookies, etc).

It struck me that these kinds of browser automation/integration/scripting techniques could be classified, perhaps using a pattern language. There also seems scope for providing tools to auto-generate some of these tools given knowledge of URL structure, parameters, etc.

So I'm collating my notes here before writing up something more concrete.