Use Google Webmaster Tools To Improve Your Website
It's free! And whilst it may not improve your rankings on its own, Google does infer on its sign-up page that it can improve your site's visibility in Google search results.
Google Webmaster Tools provides you with detailed reports about your pages' visibility on Google.
To use these tools you need to create a Google Account, and once you have verified your site you will see lots of useful information that Google has about your site.