Three-Letter Acronym Dearth

I was looking for an unused three-letter acronym recently. The reason is classified, suffice to say that during the course of my search, which consisted of typing random three-letter combinations into Google, I became more and more convinced that such a thing doesn't exist. I finally gave up in frustration when 'AHF' turned up the unlikely 'Aboriginal Healing Foundation'. Who knew? (FYI - I like saying "who knew?")