My website has produced almost half of my customers. I advertise in some local chamber of commerce type online business lists and get a great return on it. Most of my customers that I did get from my website have stated that they like to lookup companies online and if they have a good website then they will give them a call. Some of them will email directly from the website and if they get a prompt reply it's better than having to call.
Remember that the web is todays yellow pages. I'm the same way, if I need to hire a company for a service I do a search for their website. With no website I would never know the company existed; therefore, I would not become a new customer.
Granted, word of mouth is still the best advertising you can get, but even with word of mouth, it's better to have a friend tell a friend to checkout your website. For me anyway, it's more convenient.