It's also possible to spin with just a stick. A straight stick with about an inch of a branch on one end, that makes a hook. You hook it into the fiber and run the stick along your thight to twist the fiber. Wrap finished fiber below the hook and continue. Great way to start spinning, actually, because you don't have the problem of the spindle dropping to the floor!
I've also seen a primitive drop spindle made with a rock and stick, literally! You use the rock, lashed to a stick, for weight as a drop spindle, and wrap the finished yarn in a figure 8 around the stick. Hard to explain, but very cool when you see it/figure it out.