One of the beauties of google's system is that they try their best to keep keyboard shortcuts consistent across their products. (There's even a lab version of the search that enables keyboard shortcuts!) But if you forget, there is only one shortcut you have to remember. Pressing the "?" key on any google app brings up the shortcut list in a nice, easy to read popup. So remember this, especially on google reader and calendar, where you tend forget the shortcuts you don't use often.
