Several rules I absolutely hate for passwords:
* Maximum number of characters (bonus points if it's 8 or less).
* Require a special symbol, but only !@#$%^&* are allowed.
* Can't reuse your last 5 (or some other number > 1) passwords.
* Maximum number of characters plus requiring a number, a lower case, an upper case, and a symbol.
* Last but not least: Websites with maximum number of characters for password that silently discard whatever characters go over the length. And yes, I did encounter this one. At least the limit was 30 characters, so I guess it could have been worse.