If you are a Google power user then you already know all of the keyboard shortcuts so that you can get things done quickly. However, for those of us who have never investigated to find the shortcuts then this is the page for you. Smallwire has put together a nice list of keyboard shortcuts for all of the Google applications that have been released.
The reason it is so nice is because they sorted it by application, so all you have to do is look for the Google services that you use and see how you can become more productive. They provide shortcuts for GMail, Calendar, Reader, Writely, Video, and Maps. I think that covers all of the popular Google services.