Keyboard shortcuts across OS X and applications are an amazing productivity booster that have proven to be worthwhile, notwithstanding the sometimes arduous task of first memorizing them.
Is there a setting, app, or hack of some sort that would allow me to go about my business as usual and display any extant key combination as actions I perform match mapped shortcuts? This would stimulate passive learning of keyboard shortcuts -- and for ones most relevant to the user no less! Keep track of my actions so that I could assign shortcuts to series of actions would really be something.
What aspects of the OS libraries available could a developer use write such software?
Something like seeing the shortcut next to the menu item, only when the menu isn't used... e.g. something that would flash "Command + L" each time I click the address bar of a browser, or "Command + Shift + D" each time I clicked "Send" on a mail message.