Here's a nifty Adobe AIR application that provides you with lots of shortcuts for most of CS4 software, including Photoshop, InDesign, SoundBooth, Acrobat Pro, and more. I say most because the app doesn't include shortcuts for Bridge and Adobe Camera Raw. Still, for the price (free!), it's great having dozens of Photoshop shortcuts at your fingertips there on the desktop.
If you don't have Adobe AIR installed, you'll be prompted to do so. But that's easy enough. Plus there are lots of additional useful AIR apps that you may want to take advantage of. You can download the application here.