This was mentioned on another thread somewhere but I tried it last night up the driving range and it works a treat. I have been driving the ball pretty well recently so assumed my impact position must be pretty close to the centre of the clubface so, when I saw the tip about wiping some spit on the clubface so hat you could see where the ball had actually struck the face - I was surprised to see the resulting ballmark half an inch or even more, towards the heel - the ball still flew relatively staright and far BTW

So insted of lining the clubhead up with the ball directly in the middle of the clubhead, I moved back half an inch so that I was more lined up with the toe end of the club - the result was that the drives literally exploded of the face and the ballmark was smack on in the centre, the drives went a good 20yds further.

So - give it a try, wipe some spit across the clubface with your thumb before driving, and see where your ballmark is - you may be surprised like me!