I'm an immensely un-superstitious person… except when it comes to dice, because, hey, dice superstitions are fun. Personally, when I'm playing, I don't like to touch my dice when I'm rolling them, putting them in a roller instead. This started when I was playing in a 3.5 campaign and always seemed to roll really badly until I started trying this. Even my DM commented on how it seemed to improve my rolls.
I don't usually bother with my dice-roller when I'm refereeing, though. I haven't "noticed" anything really being skewed when I roll the dice by hand as a referee either. That's probably because I bought some GameScience dice, but it's fun to pretend that it's because I'm not rooting for one side or another, so the dice can't skew one way or the other to disappoint me.
How about you; do you treat your dice differently depending on whether you're a player or a referee?