"Power your Website Search with Google" That's what Google says on its Site Search Service.
What is Google Site Search?
Google Site Search is an edition of Google Custom Search specifically designed for businesses looking for a hosted, extranet site search solution. This product lets businesses harness and customize the power of Google search for their own websites. The cost starts from $100 and more depending on how many web pages you need to search.
Now, Google has added a new feature "On-demand indexing" that lets their customers of its Google Site Search service more rapidly include new web pages in search results.
To check, how it works? click here