I can't get an ambient occlusion bake to work with my file; every time I try to bake, Blender crashes. I'm using cycles render, and my object is pretty low-poly. There might be some weird geometry in it, but the UV unwrap worked alright.
I'm using Blender 2.78 on a MacBook.
I've tried having the image texture node selected, both edit mode and object mode, checking and unchecking "clear", and creating a blank texture image to put the UV onto.