I used to work for a self-proclaimed genius. One thing he drilled into my head, however, was that “one random pass is good enough,” because you couldn’t really get more random. And as a corellary, he only believed that we needed to encrypt things once; you take a document, or a password, or whatever, and encrypt it, and it’s essentially unbreakable.
I’ve been taught differently now. Basically it’s true that undoing encryption hasn’t gotten much easier, but it might be difficult to survive a dictionary attack where they use the same encryption on your password that you used; the goal is not to find out what your password is, but rather to get past the password. So this author recommends encrypting the password ten times. What that would do is essentially multiply-by-ten the time it would take to build the password list. ( They also recommend several other steps; I recommend you read their article). And it also multiplies by ten the number of keys the cracker has to try; one for each level of encryption.