I was just sitting behind my kit and thought about using crash cymbals for hi-hats. At first I tried a couple of old Sabian 16" crashes but finally decided I mostly liked the sound of a pair of old Pearl hats (14") with a Sabian Pro Sonix 16" crash (bell down) in the middle. It's quite a trashy sound but it's easy to get a chick out of it from just hitting the top hat and not striking the crash in the middle.

What are some of your unusual hi-hat combos?