Look around at the many SEO companies promising a lot for very little and many will say they will submit your site to thousands of search engines. Please do not be tempted to take them up on this offer. First, there are only a few search engines that matter. The rest of the thousands are probably FFA sites that you will unfortunately be listed on (which will then earn you an overwhelming amount of spam email with no other benefits). Second, you do not even need to submit to the major search engines. Google, Yahoo, and the like, will likely find your site FASTER if you have a link to the site from another web page that has already been indexed by the search engine. If that page has a decent PR, it will likely be recrawled by the search engines fairly often, so your link will be found quickly. And since backlinks are very important to ranking, getting them is a necessary task anyway. So rather than submitting, simply find an indexed web page or directory that will list your link.
One more point: Whether or not you choose to submit to the search engines, keep these things in mind. You do NOT need to submit more than once. And you do NOT need to submit all of your pages. The links on your homepage will guide the search engines to the interior pages. Make sure your linking structure is sound (i.e. your interior pages can be found by following links) and your interior pages will eventually get indexed naturally by the search engines.
In summary, do not waste time or money on these search engine submission schemes. Simply add links to your sites to already indexed sites, or if you really want to submit, then manually submit your homepage once to each of the major search engines. Then move on to the more important tasks of SEO.