To keep the spirit of this post succinct: no one likes stale content.

Update your website regularly.The search engines love new content and consider the site to be relevant and new, and therefore, rank the site higher.

Here are a few ideas for fresh content:
1. Literally rewrite the content at regular intervals
2. Integrate a Twitter or Facebook feed
3. Integrate a news feed
4. Keep a blog either on the home page or linked from the home page

5. Include a calendar of events

Whatever it takes, keep the content updated.