A good question, and one that isn't asked enough. When deciding if you need a website, you need to think about the type of business you have. Most businesses will benefit from, at the very least, a simple website describing the business and giving contact details. The type of business you have should dictate the size and scope of your website.
One good idea, before drawing up your plans for a website, is to see what your competition is doing. That's not to say you should copy them - but, for example if you have a restaurant/bar and don't know what features you can build into your proposed website, maybe a look at other restaurant/bars will give you an idea.
If in doubt, contact Bodu Web for a free consultation. We'll analyse youre business needs, and propose appropriate solutions to fit your budget.