If you are running a SharePoint site and notice the search results seem inconsistent because they return all the pages on your site, you may notice the results all point to your global or current navigation.

To prevent the SharePoint search crawler from indexing the portions of your page that contain navigation links, all you need to add is:

class="noindex"

To the div that wraps your navigation sections.

You can use this “noindex” trick around any section you want to have search exclude the content.

More details are available at this blog post by Corey Roth:

http://www.dotnetmafia.com/blogs/dotnettipoftheday/archive/2011/01/26/how-to-exclude-part-of-a-page-from-being-indexed-by-sharepoint-search.aspx