The Acratech GV2 is probably the best ball-head I have seen. It is manufactured in USA and is not always readily available in the UK.

It is very well manufactured and feels as robust as it looks. The rubberised knobs are easy to use and the ball, which is completely grease-free, has a tension control which stops your precious camera and lense from flopping about when readjusting position. The head is fitted with a quick release plate which necessitates the fitting of a acra-swiss type plate on all your cameras and lenses.

The head is able to be used as a gimbal by rotating the ball into the slot and this (according to acratech) can be used for lenses up to 400 f/4) The only drawback, I find, is that with a longer lense fitted, like many ball-heads, there can be a small amount of creep when tightening up the knobs and the lense does need to be held tightly in position. But saying this, even with my 100-400 zoom and canon 1D Mk 2N on I have confidence that the head will not move when locked up.