What kind of website? if it's a blog then use submit you content to social bookmark sites like delicious,stumbleupon,etc.
The purpose of submitting your site to this directory or social bookmark is to create a "back link" to your website. It means search engine bots will find the link to your website faster when they crawl all these popular website. Apart from submitting to these directories, you can also use iGoogle and MyYahoo to put a back lnk to your website. Also make sure to use Google Webmaster Tool and Google Analytic to further improve your traffic.
p/s: be careful though submitting your website to black listed website will also affect your ranking. Another thing, for Google, there is something called "Google Sandbox". You can read about it
here.