I agree, the knowledge base is a must have. I started off with a few questions and answers in my knowledge base and build it up as the support questions come in. It gives the customer the freedom of looking it up themselves without having to wait for support (it seems to happen quite often that people don't expect an answer straight away from support, so they don't sit around and wait).

It also brings other people to your website that are looking for an answer to a question you have in your knowledge base. Keeping your knowledge base updated has more than one advantage. It also shows you know what you're doing.