While some domain names have high paying keywords, frequently the traffic isn’t significant enough for this to make a major impact on the name’s value. When the name is parked, you may generate a decent amount of revenue from targeted type-in traffic. However, unless something out of your control happens, there really isn’t much of a way to increase traffic to the name with a parked page.
One way that may boost traffic, increase revenue, and consequently increase the value of your domain name is to build a stripped down website. This is a hybrid development project where you add limited (but relevant) content, which should help you with your search engine placement. As a result, more people will find your website, and they may be more likely to click on the Adsense links, generating additional revenue. The more you continue to update your site, the more likely it is that people will find you and return.
In my opinion, the key to this is developing these hybrid sites in areas that are of interest to you. This will encourage you to post more often than if it was a mundane topic or something you didn’t care about. The more passionate or knowledgeable you are about a topic, the more likely it is that people will find you. The job of Google, Yahoo and other search engines is to present their users with the most relevant website based on their search query. If you are able to provide this, you will be placed higher. Of course there are things that make this more complicated, but that is the general idea.