If I go into too much detail here, I’ll spark some unwanted debates. BUT, I can safely say that most web directories will be seen by Google as nothing but an empty link. What do I mean by this? It means that the links you’re submitting to directories are worth very very little to Google. The average web directory, despite PR, adds little to no trust to your website compared to any other organic link.
A link is not just a link anymore. There are grades of links. Directory links would probably be considered a grade F link to Google. This doesn’t mean that it will be detrimental to your website; it just means that it’s not even worth it.
The internet is flooded with online web directories. It use to be so easy to just spam these directories and fudge the SERPs on Google. Websites linking to you are now evaluated by Google to see how legitimate that website is. Since most directories approve pretty much any website submitted to them, very little trust can be weighed upon them.
Directories still worth submitting to:
Yahoo!
Dmoz