Sites that promote submitting your website to tons of URLs for a fee are not worth a dime. If your site is unable to be naturally discovered and added to a search engine without being submitted to a search engine, you've got problems. I would choose to submit my site manually to the big search engines, Yahoo, Google, Live, and then let the bots do the rest. Having other people link to your site so that your site is discovered naturally is just as good. Choose the sites that introduce your website to search engines wisely. If they are the same topic as your site, it will be an awesome bonus.