Thanks to the somewhat recent expansion of CSS rules, pretty much any font can now be used on a website. This makes for a lot of really cool web typography that we want to identify. WhatFont is a bookmarklet that makes these fonts very easy to identify.
Sure, you can use tools like Firebug or go digging in the CSS stylesheets to figure out what font is being used on a webpage, but WhatFont makes this ridiculously simple by allowing you to click the bookmarklet and hover over any text on the page. A little overlay will appear (as depicted above) with the name of the font being used so you can go look it up and potentially use it yourself. While WhatFont isn't the only way to get this information, it's definitely the easiest and most elegant method we've seen.