Last year the developers of Opera decided to use WebKit instead of its own Presto engine, which incidentally is also used by Google's Chrome browser. Together both these companies are working on creating a new rendering engine known as Blink which is inspired from the WebKit.
Now, since the rendering engines of both these browsers are the same, Opera users have the option to use Google Chrome extensions. It's a great deal since you get the goodness of Opera and the immense choice of extensions from the Chrome Web Store.
Learn how to install Google Chrome extensions in Opera.