Consider updating your website to make it "sticky". What does this mean? When your website is sticky, it means that the content is interesting and unique enough that people want to hang around, and come back often to see what else you may have added since their last visit. Other websites will link to yours as well when they see that you have something you just don't find on other websites, especially when it draws a crowd.
Search engines love "fresh" content, which is another reason you should consider adding more pages to your website, or updating the pages that are already there. If your website gets stale or stagnant due to lack of fresh content, your rankings are likely to slip over time.
There are lots of reasons you should be putting your ghostwriter to work! Content, content, content - it's what the world wide web is made of!