In my opinion, Google, MSN and yahoo are the only most productive search engines. When you visit all these search engines submission sites, they claim to submit your site to 100s of search engines. Most of those search engines are what I call dead search engines. You will hardly receive any visitor to your site from those engines. In my opinion, I rather pay to have my site list higher on Google and Yahoo than paying to be submitted on all those 100s of search engine. This is just my 2 cents.