I've been digging into the Command infrastructure in WPF lately and I really like the way it works. Essentially it is a way to separate the idea that you have commands that a particular applciation can execute and the ways you start a command (e.g. menu, toolbar button, context menu, hotkey, pen gesture). WPF comes a standard set of commands that are commonly used (e.g. New, Close, Copy, Paste, Cut, etc.). You can define your own commands fairly easily as well.
