To change the theme for Google Chrome you will need to replace the default.dll file with the new theme file. Location for theme folder are as follows Replace C with your Windows directory, UserName with the user name you have installed chromed with, the number is the version for Google Chrome.

Make sure to keep a backup of the default.dll, before you overwrite it with a new one. DeviantArt already has a Picthblack theme which you can use to replace the default Google Chrome theme.

Because of its fast and minimalist browsing experience number of Chrome users are increasing every day. However, for some users its default blue color theme is disappointed.

This big problem is solved by new app Google Chrome Automatic Theme Switcher. This little application changes the skin of your Google Chrome browser. The application bundles up three ready to use skins, that the author of this application found on the net, so you can make yours.

The Automatic Theme Switcher is is a free download for Windows only. Install the beta theme switcher on your PC running Chrome to choose one of three skins for Chrome—black, blue (the default), or green—and activate it immediately, without having to manually muck around in Chrome’s installation folders.

Alternately, you can manually download Google Chrome themes here.

You would like to read my post How to install themes in Google Chrome if you don’t know how to install them.
IMPORTANT: Do make the backup of the original theme file before replacing it with these new ones.

1 – Go Green

A mix of green colors in a truly “Green” environment. This is a theme for all of you who care about our planet. Go Green!
Download | Theme Author

2 – No Icons

A stab at a Google Chrome theme without the icons on the bar. I could only fit 4 characters per button so…
Download | Theme Author

3 – Mac V1.0 Theme

The theme has been inspired by Mac Osx
Download | Theme Author

4 – BlurkMAC – Mac OS X Theme

Download | Theme Author (not Available)

5 – BlurkDev DeviantART Theme

Download | Theme Author

6 – Black Window Live

Download | Theme Author

7 – IE7 Google Chrome Theme with Vista/Aero look

Download | Theme Author (Not Available)

8 – Google Chrome Firefox Vista Theme

Download | Theme Author (Not Available)

9 – Google Chrome Milk Theme

This is a theme was made to blend with the Milk 2.0 msstyle for OS X.
Download | Theme Author

10 – Safarish Theme

Anyone likes Safari here ? No ? okk.. anyone likes graphics/colors of Safari here.. For them we present Safarish.. The Safari like Theme for Google Chrome
Download | Theme Author (not available)