Email is the Next Big Thing. The price of a few international phone calls will pay for a month of Internet access, letting you handle orders and inquiries from around the world. Eliminate telephone tag and voicemail. No more spending an afternoon returning each other's phone calls. If they'd sent you email, that wouldn't have happened.
Widespread use is still in the future.
Much of the world has little or no Internet access, even in the most 'wired' parts of the industrialized world a minority of people use the Internet. But it's a minority of 100 million people, and it's still showing double-digit monthly growth rates. Getting on the Net today won't magically double the size of your business tomorrow. However, considering that the concept of 'surfing the web' was unknown five years ago but is a cliche today, it's a good bet that in the very near future people will use the Internet as readily as they use telephones today. Websites are expensive.