A Greasemonkey script (configurable to select which search engine's results to add) which adds a Google (OpenSocial) Gadget that uses Google's AJAX Feeds API to fetch an RSS (ideally OpenSearch) feed of search results as JSON and inserts them in a floating box on the side of Google search results pages.
Inspired by DeeperWeb, which looks to be built entirely using Google's AJAX Feeds API and Custom Search Engines (plus a little bit of extra code to generate the tag clouds from the search results).
Install the Greasemonkey script then try a Google search (note: you might have to search from Firefox's search bar, as Google have started using AJAX-y searches from the front page that don't use query strings) - the extra results should show up in the top-right-hand corner.
Note that it sends your search query to my server to fetch the results, so better disable the Greasemonkey script once you've tried it out.