If you're a designer or just curious to see what fonts are used on your favourite websites, the free Chrome extension 'What's the font?' reveals this information easily. After installing the extension you just need to right-click the highlighted text with the font you want to identify and choose the menu option for 'What's the font?'.
Of course you can delve into the page's source code and find that information yourself without the extension, but that takes more time and can be confusing if the page uses many fonts. The big drawback to this extension for me is that it can't identify fonts in images. We covered a similar-sounding web app called WhatTheFontIs years ago that can find fonts in image files, but going to a web app and uploading a file isn't quite as convenient as a browser extension where you only need to highlight text.
As long as you can consign yourself to visiting one of the above soluions for identifying fonts in images, 'What's the font?' may be a useful tool and the price (free) is certainly right.