Boker has released a neck knife that is an interesting take on the whole concept. The paracord lanyard is attached to a spring clip that holds the body of the folder; when you pull it free, you're holding the knife free and clear. The knife is never really "sheathed" as such.
The blade pivots laterally into and out of the protective frame. To release it, you squeeze the end opposite the pivot, which releases the blade to swing. It locks shut just as it locks open. It's tricky at first, but with practice I got so I could do it easily with one hand.
I'll be doing a full review of this, but thought you'd enjoy a sneak preview.