Chrome: Select Search is a Chrome Extension that pops up a ballon with a number of search engines when you select a block of text. When you double-click on a word or phrase, you can quickly pop open a search in Google, YouTube, Wikipedia, Binsearch and others.
If you find yourself continually opening new tabs to search for content you find on a page Select Search is a handy little tool to have around. When you select a block of text, a small pop-up appears and you can click on icons to search Google, Google Images, Wikipedia, Twitter, Binsearch, Facebook, eBay, Google Maps, YouTube, Geograph, Flickr and Nzbindex. You can add and remove search engines in the options. New searches are done in a new tab so you don't have to worry about losing your place.