Google has released a beta version of its Chrome browser for Linux and Mac OS X, you can find download links over here. Also new are extensions in Google Chrome, these are available for the Windows and Linux edition.
When we first launched Google Chrome in September 2008, we knew that we wanted to make it easy for you to customize the browser with extensions. We also wanted to make extensions easy to create and maintain, while preserving Google Chrome's speed and stability. Extensions on Google Chrome accomplishes all these goals: they are as easy to create as web pages, easy to install, and each extension runs in its own process to avoid crashing or significantly slowing down the browser.
If you're on a PC or a Linux machine, you can check out more than 300 extensions in the gallery, including a few cool, useful and cute extensions. Extensions aren't quite beta-quality on Mac yet, but you will be able to preview them on a developer channel soon. And if you're a web developer, you can learn more about writing extensions for Google Chrome on the Chromium blog.