Here are a few sites that offer free automatic search engine submissions for your website:

JimTools - Submit your site to 46 search engines, 144 directories, and 1,600 FFA pages.

SimpleSubmit - A very simple search engine submit tool. Also, some has some search engine basics, promotion tiops, and an explanation on how their submission tool works.

Free Web Promotion - Submit your site to 25 search engines. You have to register to submit your site but registration is free.