Well, I've certainly never seen a vehicle like this before. It's DARPA's DiscRotor, a weird combo of helicopter and airplane that has the ability to hide its rotors in a spinning disc.

The DiscRotor is still in the planning phases, with the below video just showing a concept rendering. But if and when it's built, it'll offer "more mobile, faster hover vehicles that can get troops in and out of critical situations in a hurry." Also, it sure is cool lookin'.

Aviation Week via Gizmodo