Google views a regularly updated website as one which has the commitment of the owner. This gives it a perceived value, and will contribute to how relevant and current the content of the website is. Google likes this because a website that has the commitment of the owner, and is up to date, makes for good content for their result lists (for searches). So they will want that website to appear toward the top of the result lists and so they give it a higher ranking for your keywords. Furthermore if you update regularly Google recognizes this when it returns and indexes your website the next time, so it returns more often.

Update your website regularly. Weekly is a good frequency, and try and get your home page to reflect those changes. An article (or tips!) facility is a good idea, or a quote of the week which you can manage yourself. For those who contribute, then get in and change your home page content if you can. Added to your efforts at increasing your link popularity, then you will be doing a lot towards increasing your success on search engines.