It's important to give your visitors information they can't find anywhere else. If you're the only source for a certain type of information, people will flock to your web site.
Most people like to find good deals on software for their computers. If the software is free, that is even better.
It's a fact, people like to win things. If you can fulfil that need, people will stop by to visit.
Create a directory of web sites on a particular topic that is related to your target audience. People will visit because they will find what they're looking for, all in one place.
Most people love to get free information that they're interested in e-mailed to them on a regular basis. This saves them time and money.
People like to have a place were they can have discussions with others on a particular subject. You could add a chat room or message board to your web site.
One of people's basic needs to survive is money. When you offer them a free opportunity to make money they'll line up to visit your web site.
When you offer a utility that can solve a problem, people will visit your web site. The utility could be a free auto responder, e-mail account, search engine submission, etc.
Supply news stories related to your web site. People want up-to-date news on the topics they are interested in. They will also be interested in visiting your web site.
Have you ever been to a store and you jumped at the chance to get a free sample of food? This same concept will also attract people to visit your web site.