I can do this with my right toe, my neck, my shoulders and my right wrist!
It's similar, in that I don't need another appendage to do the work.
Right toe: I bend all my toes down then flick up quickly. It will NEVER fail to crack.
Neck: I can bend it slowly to one side, then do a snap back to the other side and it will crack. I tend not too do this too many times in a row, it begins to not feel too good after about 5~.
Shoulders: Left shoulder rotates around and constantly cracks. Right shoulder I put my right hand on the back of my neck and bringing my straight with my torso and you hear one big loud pop and you can see it on my arm too, it suddenly jerks back into a different position.. hard to explain, but yeah.
Right wrist: Make a squid shape with my fingers, pull them back down to the inside of my arm and I snap it back.

None of these ever fail to pop…yet it does begin to hurt after some repetition, so I stop.