Google  
 Google Web Search and Site Search
 
Web Search Options

Custom WebSearch   Google Free web search and site search
Google's Custom WebSearch service enables destination sites, portals and vertical portals to offer award-winning web search services on their site. Fully customizable with language, country and specialty searches. Put the full power of the web at your users' fingertips.   A no-cost way to add Google WebSearch and optional Google SiteSearch to your site. Help your users find what they’re looking for on the web and within your own pages. The easiest version to implement is our copy and paste Google Free web search service. Just a few lines of code copied into your site and your users have access to a Google search of the web.

Add the URLs you want to search and you can offer Google Free site search as well, making it easy for your visitors to search within your site.

With an additional couple of steps, you can add your logo and customizations to the search results pages. This service can be up and running in five minutes.

(Google reserves the right to sell ads on all Google Free search results pages.)
Silver/Gold Search  
Google WebSearch and optional Google SiteSearch are intended for small to medium size sites. Offers customization of many elements of your results page and the option to sell advertising.  
University Search  
Google SiteSearch with optional Google WebSearch free for universities and educational institutions. Full customizations available with no ads served.  

Site Search Option

Google Search Appliance
Fast to deploy and easy to run, the Google Search Appliance puts the power of Google's award-winning search engine to work for your corporation.