I have to keep every item on my desk straight and either perpendicular or parrallel to the others, drives me nuts!!

Other than that - none, although when I was a kid I used to always step on the same number of coloured tiles when I was out shopping with my mum - used to drive her mad as she'd have hold of my hand and i'd be leaping all over the place!!

Oh and I used to devide words up somehow so that they either made equal letters of finished with the centre one - I've forgot how I used to do this and it's just made me think what a strange child I was