Little that we know about, that is. Blackbird was black for a very long time. As for one program that we do know a little (more) about, there's X-37B: http:/

Little that we know about, that is. Blackbird was black for a very long time. As for one program that we do know a little (more) about, there's X-37B: http://www.physorg.com/news189528362.html http://www.physorg.com/news189528362.html http://spaceflightnow.com/atlas/av012/100402x37update/ http://spaceflightnow.com/atlas/av012/100402x37update/ And the X-43D and X-51A Waverider and DARPA FALCON hypersonic aircraft, and various other X planes. Various known and likely various unknown black UAVs. And whatever Burt Rutan is up to.