Join the Google Cast Chrome Extension Beta Program
Google has opened up their Beta version of the Google Cast extension for the Chromecast. If you don't know, you can cast tabs from a Chrome browser to your Chromecast connected display. Today, they've released the beta version of the extension to the public, and you can grab it right now.
UPDATE: Get the newer non-beta public version here.
Using the beta extension may present some bugs, but you'll get to try out any new features or improvements well before they make their way to the official extension. While intended mainly for devs who want early access to upcoming APIs, the beta is perfectly suited for softModders. Just know that if you're having any issues with the new extension, you can easily install the stable one as well. Give it a shot!