Here’s a secret: OS X has a password generator built-in, but many people will never even see it. Here’s how to make it easier to get to.
The Password Generator usually only pops up if you click the tiny little “key” symbol that appears if you create a new account, or a new item in your keychain; it looks like this:
If you click that key, you get this:
And that’s the Password Generator. It’s capable of creating passwords of varying strength and memorability (click the Type drop-down to see). It’s quite useful to have around, especially when you’re signing up for something new on the web and need a nice strong password to protect it with. (You do use different strong passwords for every site, don’t you? You wouldn’t use the same password everywhere, would you? Cos that would be bad.)