The Canon Speedlite 470EX-AI is a unique motorized on-camera flash that (somewhat creepily) measures the room and aims the flash head to bounce out the most even light. It works! You can use it manually too, of course, with some servo control or none at all, as you prefer. And its specs are pretty decent, too, with a guide number of 154 (ISO 100, full zoom) and coverage from 14mm to 105mm. For better or worse, nothing else does what this flash does. It's in excellent condition, with its original case, diffuser, and stand.