The behavior I'd love to see is for D or Cmd+D to mean "Don't Save Changes".
Is there any way to accomplish this?
Try and see if you have the “Darcs” bundle installed; disable it if you don't need it (or probably don't even know what the heck darcs is ;) or change it's invocation shortcut to something other than ⌘D. If you don't have Darcs, then some other bundle item might have snatched the ⌘D shortcut. See [here][1] and [here][2] for an explanation.
Soryu
[1]: http://macromates.com/ticket/show?ticket_id=2EF951A6 [2]: http://macromates.com/ticket/show?ticket_id=67031851