Over the years, I have setup a number of websites. Once I setup a site for someone the first question I usually get is “I don’t know what to write about”. There is a site that looks like it would be useful. Check out Answer the Public.
This site aggregates bing and google search history to tell someone what people are asking about a particular topic. For instance, look at a search for ‘Apple Pages’.
These are the “long tail” questions people are asking in Bing and Google about Apple Pages. This gives a site creator an idea of what people are looking for so they can taylor their site to give them what they want. The more of these questions you cover in your site, the better chance you will get the hits.
This can be very helpful in giving someone ideas for what to write about and post on your website.