Between 50% and 60% of the people using the Internet today do not have high-speed broadband access. Yet many Web sites cater only to the 40% that do. Then they wonder why their sales figures are so poor. Although it’s tempting to add every whiz-bang feature into a Web site, if you do, you are undoubtedly sacrificing profitability for “techno-appeal.”

As the Internet has become more popular, more and more software applications have moved onto the Web. To give users an experience that rivals what they get from their PC software, browser vendors have had to give developers a way to program and extend the browser interface. A programming language called JavaScript is one popular tool for client-side (browser) scripting.

Unfortunately, every vendor implements the JavaScript language differently and defines the rules for manipulating the browser differently. This situation makes it extremely difficult to develop a rich user experience that works across browsers. As a result, you should be careful about adding features to your site that rely on JavaScript. For example, you should never use a script-based menu system as the only way for visitors to navigate your site. Search engine spiders cannot follow program code, so JavaScript menus essentially slam the door on the search engines.

If you think back on your own browsing experiences, can you remember a time when you got some kind of scripting error while navigating to a Web page? How did you feel about that site after you got the error? Would you want your visitors to have that feeling about your site?

The fact is a lot of scripting is totally unnecessary. Also, some browsers don’t support it, and many people intentionally turn it off for security reasons. If you do use scripting, use it sparingly and be sure to test it on all the browsers you can.

Plug-ins are just as bad. For one thing, they require your visitors to download a program that will run on their system, and some people find that idea just plain scary. Spyware and other nasties have made people skittish about downloads, and for good reason.

For example, Flash is a commonly employed plug-in that requires a sizable download. Realistically, Flash animations are cool the first time you see them, boring the second time, and annoying every other time beyond that. Never, ever use a Flash animation as the only way for people to enter your site. It is like locking the front door of your business and requiring customers to get a key from somewhere down the street.

Use animations only when they make sense as part of the content, like for demonstrating how something moves. Frivolous animations of any kind are annoying to most people. If you are trying to read the content of a page, the last thing you want is a distracting graphic flashing in the periphery.

Use sound as you would use an animation: only when it supports the content. For example, if you sell duck calls, you could include a sample of what each one sounds like. But that sample should only play when the customer clicks a link requesting it. Do not under any circumstances force people to listen to music while surfing your site. There’s a strong possibility most of them will hit the Back key and never return.

The bottom line is that you should think about your audience. Simplicity is not a bad thing. Some of the most popular sites on the Internet like CraigsList.com and Yahoo.com are simple and straightforward. Plus, they are usable by people surfing with any type of connection, even dial up. So the next time you ponder adding some “cool” new feature to your site, first ask yourself if it is going to add anything to the bottom line.