I've always used the same PIN for everything.
While there's true wisdom in using different passwords from site-to-site (yeah, I know...) I've always figured PINs are fairly secure, since not even bank employees can view them.
That being said, I'm sure there's an obscure example somewhere of how somebody had problems from using a single PIN, but ever since when I established the PIN on my first debit card back in 1990, I've used the same one, with no problems. After using the same number for that long, keying it in is almost instinctive... LOL.
(Side-note: There is one example I can think of how having different PINs could be useful, and that's when you are in the habit of giving your PIN to someone else - for example, you might be fine with your 'ex' having your debit PIN, but not your credit card PIN (or vice-versa). In this case, though, the problem is still easily avoidable...)
