This is something that's been tickling the back of my mind recently and I thought I'd put it down on paper to see what it looked like. I think the idea behind it is sound, but I can't seem to find language for the feat that I like. Here's what I've got so far:
You always have a backup plan.
Prerequisite: Int 13+ or Wis 13+
Benefit: Whenever you use the Ready special initiative action, you may ready two actions instead. You may still only take a single readied action per turn, but may specify two actions with two triggering conditions and react to the first the occurs. For example, you might use the Ready action to shoot your bow if the thugs you're fighting draw weapons or to move to cover behind a pillar if one of them begins casting a spell.