Try This Search On is an extension installed through Greasemonkey that lets you search multiple sites for your search term with one click. You can search the likes of Google, Ask, MSN, YouTube, Wikipedia, Flickr ... the list goes on. It all sits very neatly at the bottom of your window (or you can choose to display the bar at top), so it's extremely unobtrusive, but delivers powerful results.
There's really no magic to it, but enter a term and start clicking to find results on other sites. It's that simple and it's fast. Click the "?" to customize Try This Search On, or the "x" to hide the bar.
Not only is this tool a valuable time-saver, but for Web professionals, this serves as a reminder to get your content and your brand spread across the Web. Customized search tools like this are becoming quite popular with users. That means you need to have a presence on sites like YouTube and Flickr, and multiple shopping sites. (Try This Search On supports Amazon, eBay, Yahoo Shopping and more.)