Just discovered I Have Macro LOL on the wowace forums, and have to say it's one of the handiest I've found in a while. It's the sort of functionality that I just don't know how I did without now that I have it.
IHML - WowAce Wiki
Basically detects when Bigwigs bossmods are loaded for fights that have a related macro or item use (think Naj spines, totem targetting, or anything else that you might only want on your bars for that one fight), and automatically loads the relevant macro onto that fixed bar location or keybind. Can also do so based on zone detection for one button daily quests too.