If you're a fan of Google's Chrome browser that in its eight iteration wowed a lot of people, you should consider Eli Grey's extension that mimics Voice Search functionality on iPhone and Android devices. Aptly named Voice Search, the free add-on installs itself next to Chrome's address bar. Just click on a small microphone icon and speak aloud your search query.
Like, saying "wikipedia Apple" to bring up the Apple page on Wikpedia or asking for a Google Maps location by saying "google maps" followed by an address. The author warns that speech input is "very experimental," so expect glitches. Also, try to speak clearly and in standard American English accent for best speech recognition results.
The extension comes with presets for Google, Wikipedia, YouTube, Bing, Yahoo, DuckDuckGo and Wolfram|Alpha and you can add custom search engines as well. Another cool treat: Voice Search puts the microphone icon on all web sites using HTML5 search boxes, like Facebook, Twitter, reddit, and GitHub, allowing you to easily search by voice when using those services as well.
The extension works on stable Chrome 8 release, but it can be made to run on beta and developer Chrome releases, which requires a little bit of trickery explained in release notes. If you're eager to try out Voice Search for Chrome, download the free Voice Search extension on the Chrome Web Store.