Inform / Educate
Of course, one of the primary functions of a website is to inform and educate the visitor. You obviously want potential customers to be able to visit your site and have a good idea of what you can offer them. This may include an "About Us" section, but should definitely include information about your products or services. Pictures, product specs and catalog downloads are always helpful as well.
Not only do you want to have this information available to your visitors, but it would also be nice if it was well organized, easy to find and cleanly laid out. No size 8 font, no red text on black backgrounds, and no never ending layers of drop-down menus.
A second major function of a website should be building credibility. For some this will include project photos and descriptions, for others it will include client or project lists, yet for others it may mean presenting case studies.
Our favorite credibility builder is a testimonial section. Sure, that may take some time and work, but combine some solid testimonials with some of the above mentioned features and you've got a real formula for A+ credibility.
Collect your check!
Well, maybe it's not quite that easy. While it would be nice to set up a site and just wait for the phone to ring and checks to roll in, that's just not reality. What a good website can do, however, is present your company in a favorable light, creating a mood where the customer wants to buy from you, and you have to do less selling. No one likes to be sold, but everyone likes to buy.
If you take the time to create content for your site that provides value to visitors before they buy, i.e. offers solutions, instead of just spewing about how great you and your company are, you'll come across as an expert, build the highest level of credibility, and have a real "secret salesperson" working for you 24/7, 365.