If you like theming your apps but aren't a fan of the themes in Google Chrome's Gallery, Chromethemes.net has a nifty, easy-to-use tool with which you can create your own themes.
The only thing you need to have on hand before starting up the web-based tool is about 4 image files (in PNG format) for the frame, toolbar and various tab backgrounds. See my above theme for an example of how they're divided up in the window (okay, so the theme itself is hideous, but the stark difference in the colours helps explain what area of the window each PNG is assigned to). Alternatively, you can just leave the image slots empty and chose colours for each area from the "Colors" tab. When you're done, just hit "Pack" and download your theme to see how it looks. It's extremely simple to use, and a cool way to really personalise your browser. Hit the link to try it out.