Directories are very popular and are widely used by people as a source of information. Web crawler search engines may also have better chances of finding your website if it is listed with any of these directories. Most of the directories charge a fee for listing your website. Some sites such as Yahoo offer free submission as well.
An important aspect of submitting your website to a directory is to have a 25 word or less description of the website. This allows the web crawler search engines to efficiently find and include your website.
Yahoo, LookSmart and Open Directory Project are some of the most popular directory services on the World Wide Web.
Yahoo provides two submission options: Free submission known as "Standard" and paid submission known as "Yahoo Express". The free submission cannot be used for commercial websites. Also, with free submission there is no guarantee that your website will be approved for submission.
Submission of commercial websites can be done with Yahoo Express that has a fee of $299 per year. Although a majority of websites are accepted in this category, note that, paid submission also doesn't guarantee acceptance of your website. It only ensures an answer whether your site was accepted or not. For non-commercial websites there is a one-time fee of $299.
For submission of free non-commercial websites you will have to fill up a submission form that is displayed once you click the "Suggest a Site" link at the bottom of each category. In case of paid commercial websites you would have to fill up the submission form that can be accessed at http://add.yah.oo.com/fast/add?+Business