Make it decent. People who haven’t bought your app may judge your app to some extent on the quality of your website.

Home page with images and info about your app. (More than on the app store)

Quotes from great reviews (from other websites or app store)

Video of your app in use. The reason why people don’t like to pay more than 99 cents is because they’ve found that they bought bad apps.

With no trial or demo apps this is the closest they can come to see the app in action. Create from Simulator with screen capture or video camera.

Post on YouTube as well.

Getting Started Guide page – You may not need this if your app is super, super simple but the number of people confused by the simplest thing is very large.

Problem Solving or Trouble shooting page – Are there any known bugs that are being fixed? Are there common mistakes people make or don’t understand with your app?

As the complexity of apps gets larger it’s difficult to create all the features in way that everyone instantly gets.

Link to your App on the App Store so if someone comes to your site first they can easily purchase it.

Contact email link or form for feedback, bug reports, etc.