ht://Dig (http://www.htdig.org/ http://www.htdig.org/) was my favorite back before Google was big. It hasn't been updated since the rise of Google, but it is s

ht://Dig (http://www.htdig.org/ http://www.htdig.org/) was my favorite back before Google was big. It hasn't been updated since the rise of Google, but it is still a very configurable, nice search engine. Google Custom Search is probably the best bet for any site. It has a free mode for free organizations, and an ad-supported one otherwise.