You probably already know that Google offers a free search tool that you can easily place on your site. Actually they offer several different methods to add free customized search to your Web site, including Custom Search Engine and Google AdSense for Search.
You may not be aware of the free Yahoo! search tool. It’s an easy to set up process that guides you through the menus and then gives you the code to plug into your site. You can customize the search results page to match you color scheme and include your logo to link back to your Web site. The search box has a Most Popular Searches feature that increase searches by showing the most popular searches from the search box. There are useful reports available to view Search Traffic, Top Queries and Top Referrals.