I wouldn’t base any SEO or internet marketing campaign only around website directories, but there are some essential directories that I think every business website should be listed in.   These are all free directories that are pretty simple to get listed in.  I have included my favorites below:

-DMOZ - Great directory, but it takes a long time to get listed.
-Jayde - Very quick and easy submission process
-Kudzu - Instant approval
-Merchant Circle -Instant approval and very quick indexing in Google.
-Yelp - Based around user reviews
-Turnpike -Simple design but a good free directory
-Little Web Directory - Easy and fast submission process