When you search for a keyword in any of the search engines like Google, Yahoo! or Bing, they usually show a list of websites in the search results. You have to click on those links to find out how that site looks. If you are using Google, then you can hover over a website in search results to see its preview but it requires action on your part. The SearchPreview addon for Chrome and Firefox browsers adds the preview functionality to Yahoo!, Google and Bing search engines. It displays website snapshots as thumbnails along with your regular Google, Yahoo! and Bing search results. This allows you to get a small preview of the site without having to visit it first.
You can visit the Mozilla add-on website to install this SearchPreview add-on for Mozilla Firefox browser. If you intend to install this add-on for the Chrome browser, then you can search for this extension on the Google Chrome webstore. It requires restarting your Firefox web browser. After the installation and restarting Firefox, you can start using it right-away. Just lookup for something in Yahoo!, Google or Bing search engines and you would see website thumbnails properly affixed to the respective links.
You can open the SearchPreview add-on options from the Add-on options page (Ctrl + Shift + A). In the options, you can limit the number of thumbnail preview images for search results on a page, insert the popularity rankings into search results, show SP icon in the add-ons toolbar clicking on which you can toggle SearchPreview add-on etc. You can also enable or disable the insertion of advertisement results within the actual search results.
SearchPreview is a nice add-on for Firefox and Chrome and it spices up the search results by attaching the website thumbnails in the search results. I hope they add more features in the future like viewing a full size thumbnail, showing if a site is harmful or not etc.