Web directories are a great link building resource. Especially if you can find niche directories that cater to particular categories. Inbound links from niche directories, can hold a higher value than links from general category web directories. High value links contribute to page rank.
One of the best resources for finding niche web directories and specialty hubs to submit your site to, is called Search It
Any web directory that is worth submitting your website to, will most likely be a human edited web directory. The editor is responsible for making sure that websites submitted for inclusion, meet the minimum standard quality guidelines, before they are granted a listing in the directory.
This means that your website will be listed among other sites of equal, or even better quality than yours, and therefore the link pointing back to your website from the directory, will be awarded a stronger value by the search engine algorithms, which in return will award your site with merit
The real value behind web directories is in the inbound links pointing to your website. Higher page rank equals increased link value. Thats why the DMOZ and the Yahoo directory are the two premier web directories to be listed in. They hold the highest page rank of all the directories.
They also set higher standards for quality so before you submit your site to the Yahoo directory or the DMOZ, make sure that your site offers quality information and resources based on your site topics, otherwise you risk having your site rejected.
If you would like to get a better idea of what I mean, Just visit both of the directories, Yahoo Directory -- DMOZ choose the category in which you would normally list your site in, and start reviewing some of the websites listed. You will see what I mean about quality.
Submitting your website to various web directories for inclusion, is just the first step of a good link building strategy. As your site grows, you need to start exchanging links with other webmasters, who have quality websites with topics that are related to yours. This is known as reciprocal linking.
In the beginning this will most likely, turn out to be a daunting task which reaps little reward. The reason for this is because most webmasters who have quality websites with an established page rank, are very picky about the websites they link to. Don't get discouraged when you are faced with rejection, instead, just think of ways to improve the content of your site.
Don't be afraid to ask a webmaster who declined your offer to trade links, for suggestions on how to improve your site, and if they would be willing to reconsider your offer in the future. Let them know that even though you may be inexperienced, you are serious about creating a quality site
One of the best link building resources that I know of on the Internet, is the Site-Sell Value Exchange. The Value Exchange is a free membership sponsored by SBI, for the purpose of bringing together fellow webmasters who are looking to exchange links.