List Local and Global Key Bindings in Mac OS X Can someone help with a solution to list key bindings being used by an OS X application, as well as global bindings being used by all applications?

Ideally, there would be a way to specify bindings for a single key combination, such as:

Ctrl-P or Opt-Cmd-Z

as well as getting a comprehensive text dump of current bindings for all keys.

For my purposes this doesn't need to be fancy: A Bash or AppleScript would be fine. Of course, a dedicated GUI utility would be great, if such a thing exists.
I recommend KeyCue, if CheatSheet is not quite enough.

As Phill already mentioned, CheatSheet is great, because its fast, free and simple. But I noticed that for some applications (like Adobe Photoshop Lightroom) some shortcuts are missing from CheatSheet. KeyCue takes the shortcut game more serious, by showing shortcuts and their context more detailed. It helps you to create your own shortcuts and lets you exactly specify how and when they should trigger.