ncRankCheck is a little addon that helps you find downranked spells on the actionbars. When you use /rankcheck it will flash all downranked action buttons and print output to the chatframe(see image).
Install & go! Use /rankcheck to show all downranked spells on the actionbars. If you pass any arguments to rankcheck(example: /rankcheck 1) then it will also print out the downranked spells on buttons currently not visible(stealth bar for example).