TED published a talk from Robert Lang titled "Idea+Square=Origami" (18 mins):
He talks about art and it's relationship to math and engineering; its really quite amazing where he goes with it. But even if you hate math or art philosophy, there's something amusing embedded in the talk: an origami Ibex. He has two examples, here and here. He even adds details in the horns.
But just as importantly, Linux source and builds are available for the software he wrote to help him design origami. You find it all from the TreeMaker homepage. If you use it and like it, be sure to thank him! It'd be really neat if someone came up with directions for making an Ibex to keep people busy in the run-up to the Ibex release party :)