Search Cloudlet displays a list of tags and other information pertaining to your results that, when clicked, automatically refine the displayed results.
After installing Search Cloudlet, a tiny (20kb) add-on, you'll see a block of keywords above your Yahoo or Google search results. Clicking on any of those keywords (for example, 'accessories' or 'reviews' displayed for a google search for 'motorcycles') automatically adds that tag to your search and quickly re-displays results. More common tags are displayed in larger text to help you choose.
You can also narrow results by the site name or top-level domain (ie. .com, .org), or turn off the Search Cloudlet display, by clicking on a small Cloudlet bar displayed on the results page. If you search News items those options change to allow filtering by the name or location of the news source, such as "PC Advisor" or "UK".
In essence, Search Cloudlet provides fast, easy and all-at-once access to advanced search options (such as using a site: modifier in your term) that we can already use but don't usually bother with. It won't enhance all your searches, and it does add some textual clutter that could take some getting used to. But if you find yourself having to often refine or customise searches, this free tool could have real value.