Does anyone know how to do this? By extension icons I mean the icons that display for extensions on the top right corner.
All keyboard shortcuts: http://www.google.com/support/chrome/bin/static.py?page=guide.cs&guide=25799&topic=28650
I'm pretty sure any shortcut to an extension would have to be specific to that extension. In other words, the keyboard shortcut would need to be programmed into the extension's capabilities.
In newer versions of Chrome, you're now able to configure shortcut keys to launch extensions.