If you have a large site, you may want to set up an internal search engine which covers just the contents of your site. There are two options for this. If you are on a free host, or other situation where you don't have access to a cgi-bin, you can use a remotely-hosted search service, which will generally place its own ads (or at least logo) on the results page. If you do have cgi-bin access, you can install a script that can be customized to your layout. Your choice may also depend on your own current level of technical ability - remotely hosted searches are easier to set up, but cgi scripts can be more flexible, and don't require ads or logos.