Bune - I started out as centre forward, and later I was an inner. When I was a student, though, I played inter-departmental hockey twice on Sundays just for fun, and I used to play a back, which was a lot of fun :)
In my last season I played keeper a few times when ours was ill. It was an utterly terrifying experience! I don't know how you're brave enough to do it... I was v. naughty and had to stand in the goal mouth with a ciggy psyching myself up for when the marauding hoards came charging down the field towards me :-)