Is it possible to do all the marketing for your business from your website?

Maybe. Why? Are you doing an experiment? Unless that's the plan, it's hard to see any reason to limit yourself in that way. Your website is an essential part of your marketing mix, certainly. But it will combine well with other marketing ingredents:

• E mail marketing Build your house list  with your website, trade show booths, a sign-up sheet on the counter at your physical place of business, or your Facebook page. Then use e-mail to bring customers in --to your website or to your brick and mortar shop.
• Direct mail marketing Send out a postcard, and make sure that your website's address is on it. Studies show that consumers now usually check three different channels of information in the course of their decision to buy: that might mean your postcard, your website, and your shop. Studies also show that an e-mail follow up to a direct mailing can be expected to increase responses by 50%.
  
• Shows and speaking engagements Hold a seminar or workshop, set up a booth at a tradeshow, or take a place on a panel at a conference. Hand out business cards with your website's URL when you do, and you'll be bringing interested people in where you can tell them more.
  
• Your brick and mortar shop If you have a store, an office, or another physical place of business, be sure to put your web address on the sacks, brochures, and signs. Train staff to ask, "Have you visited our website?" when they check customers out.  And be sure to show your address, map and/or pictures of your place of business on your website. The two venues will support each other, and both will get more traffic. 
• Public relations When you do press releases, include a link to your website. Put your press releases on your website, too, or link to them. Again, there's a synergy there, and each supports the other. 
• Social media Have a blog, a Twitter account, and a Facebook page for your business. Link to your website from those social media pages, and link from your website to those pages, too. Encourage staff to link to the company website from their pages at LinkedIn or Xing, Jigsaw or Spoke or Ning. The links help your website, and they make your staff's pages more interesting, too. Friend your colleagues at Facebook and follow them on Twitter.
  
• Physical world networking Share your business card, and make sure your website's on it. When someone at the Chamber meeting gives you her email address, ask whether she'd like to be on your company's email list. People you know in the physical world will be more receptive to your email contacts, and they're likely to visit your website, too, if you tell them about it.
  

 Each time you connect your various marketing methods, you increase the value of each one, till the whole is greater than the sum of its parts.