Paid inclusion is usually required to get your website listed within a web directory such as the Yahoo Directory, these services are similar to traditional printed directories such as The Yellow Pages Directory. Fee structures are also similar where you may gain a priority listing for spending more. Typically, the fee covers an annual subscription for the inclusion of your website within a certain category, a pay per click fee may also apply.
The benefits of using paid inclusion for your website are mixed, some websites report higher amounts of traffic and better rankings within search engine result pages (SERPs) whilst others see it as a waste of time and money, and feel little benefit from having their website included in a website directory through paid inclusion.
In the past Google and other search engines used website directories to add weight to search results, however it is now less important to have your website featured within a directory. I recommend listing your website in as many reputable places as possible but there are faster, more direct ways to success such as pay per click and contextual advertising.