Speechify is a Google Chrome extension that enables HTML5 Speech Input on many popular websites.
With Speechify you can access many online services and use Speech Input to search and shop. Search Google, Hulu, Amazon, Youtube, and many more!
Just install Speechify, and you'll see a microphone icon added into the search box on many popular sites -- like Google and Bing. Click it, and Speechify will convert the words you speak into text. You've still got to press enter or click to search.
If you're looking for something similar with custom search options, check out Voice Search for Chrome, which we looked at last year. Unlike Speechify, you activate Voice Search by clicking its browser action icon -- and you can search a specific site be prefixing your query, e.g. "wikipedia bacon".