Although their thunder has been stolen by the search engines, directories are still a great source of both traffic and incoming links for SEO.
THE online directory, one of your first acts should be to submit your site to http://www.dmoz.org/. This directory is used by search engines (including Google) for help with their own directory of sites. It has very strict submission guidelines so read them first before submitting your site (http://www.dmoz.org/add.html). Multiple submissions or submitting an incomplete site could get you excluded permanently.
Other generic directories
Spend some time researching and submitting your site to generic directories with a high page rank and that pass link juice. There are software solutions out there that will automatically fill in submission fields for you. Believe me, after about the eighth or ninth time of writing the same site description you’ll wish you had bought it.
As discussed previously one of the factors search engines use to rank a site is the relevancy of the site linking to you. This means a site that is connected to your industry is worth more than one about a totally unrelated subject.
Directories such as the ‘ic’ or ‘touch’ networks tend to be displayed prominently in localised search engine results. Research the most popular online directories for your area and niche and submit your site.