Head Spin or Helicopter
This trick has the same timing as ball on the head, but the club is placed flat on the head, handle forwards, and then it is spun round once and falls off on the opposite side:
The trick here is to keep hold of the club for as long as possible when you start the spin off. You will find that you can actually carry the club around the first 90° of the turn, letting go when your hand is above the opposite ear. At first a head spin will seem uncontrollable, and you will probably get a few knocks from the handle, but after a while you will find the right place on your head and the right amount of spin. As your technique improves you won't have to keep hold of the club for so long, and eventually a deft flick of the wrist will be enough to spin the club accurately.
A nice way of going into a head spin is to place a club flat on your head while juggling, keep it there for a moment, and then give the handle a tap with one of the clubs in your hands - this makes it spin around, and as it drops off catch it and continue juggling.