Inclusion in Google's search results is free and easy; you don't even need to submit your site to Google. Google is a fully automated search engine that uses software known as "spiders" to crawl the web on a regular basis and find sites to add to our index. In fact, the vast majority of sites listed in our results aren't manually submitted for inclusion, but found and added automatically when our spiders crawl the web. Read here in detail- http://www.google.com/support/webmasters/bin/answer.py?answer=34397&ctx=related
Use Google Webmaster Tools. You'll find more information there. Make sure you follow the Rules & regulations, first. Also, see this link: http://www.google.com/addurl/?continue=/addurl