Hooray, the google chrome team finally made an extension system. It's currently in testing so if you want it to you need to
switch to the developer channel. The extensions are easy to make, based in HTML and Javascript. They allow you to create toolbars, or mod the browser all together. To learn how to make your own, go
here.
I played around with the system and I found it really awesome. So I made a Return to Blockland toolbar:
Download(To install it just download it, it should automatically prompt you to ask if you would like to install it)
To manage your extensions go to chrome://extensions.
EDIT: The screenshot also shows a custom theme that I downloaded from the google website.