Inbound Directory Links
Directories can be seen pointless to many users on the internet, but for Webmasters, they are a major key to building inbound links. Directories tend to accept links for pretty much every category out there, that is why they are useful to webmasters all over. It is sometimes hard to find similar sites for some categories, but you need your link out there to be seen. Directories are sites with many different categories, and are an easy way to get an inbound link.
Directories are also a good way to gain Pagerank. As most reciprical directories are high in PR, a link to your site will pass on a nice bit of PR. As content is always changing in directories, spiders tend to crawl their pages quite frequently, and sends more action to your site.
The biggest Directory is DMOZ.org. This is the largest human edited directory on the web, and has the biggest influence on rankings and PR than any other directory. So Why is DMOZ so Important? Well, google, and many other directories and minor search engines uses DMOZ' Information to obtain results. This means, if you are in DMOZ, you are in hundreds of other sites. Easy you say! Well, it is well known that sites in certain categories have been waiting 2 years for a listing, and many are not accepted. Why? Because a human edited directory can only handle so much basically. Quality of submission is a major key in whether you are accepted or not. It is very important to have a good description and keywords tag when submitting to DMOZ. I strongly suggest you go and do that now, as a listing in DMOZ is an easy raise in rankings.