Sign up for the Google AJAX Search API
Using this script you can be up and running your own Google search engine in just minutes and it's FREE! The Google Search Engine script is one of best ways to make use of the Google web API using PHP and nusoap. Best of all the Google Search Engine script only takes a minute to configure. Just upload your files, enter your web sites title, Google Key and you are up and running your own google search engine
SimilarLinks.com is an open source perl cgi script that interfaces with the google search engine using the soap API to find links of a similar nature to the url entered in the similarlinks.com search box.