Search engines love new pages. Try to add new stories, reports, news releases, and the like so that search engines feel that your site is frequently updated and thus should be frequently indexed. If your site is rarely updated, it can take months for search engines to find your infrequent new additions.
Blogs can be a particularly useful way to easily add new pages to your site — and can also provide great information that encourages links from others (not to mention all the other ways blogs can help in marketing and outreach!).