Google:
http://www.google.com/addurl/
Yahoo:
http://tw.info.search.yahoo.com/free/request
Bing (Microsoft):
http://webmaster.live.com/webmaster/WebmasterAddSitesPage.aspx
Submit Express:
http://www.submitexpress.com/submit.html
This site would help you to submit your URL to 20+ top search engines automatically.