Only high pr and relevant to your Business or website category directories may help regarding improvement in ranking.
There are still some good directories that really work and are indexed on google. But you have to pay to add your website on those directories. You will find free directories. But those free directories don't work and are considered as spam to Google.
Interesting. This search was done 2 year ago. If I google 'directory' today it gives me About 671,000,000 results (0.28 seconds) It's 5 times less...
People are getting it wrong. A quality directory owner won't just stay and wait to get suggestions. He and his team will manually search for resources, quality website and will ad them into his directory. Besides, of course there's a review fee... but the concept of "OMG, I paid $50 you need to accept my site" is wrong. You pay for a human being's time and effort to browse you website and decide if it's worth to be listed or not. After all, a directory not fulfilling it's main purpose: to offer a comprehensive end-user experience - it's not a directory.
The directories still works, just insert different detailes in each of them and don't duplicate content in any cases. FInd some good directories, don't insert the link anyway. Because web directories are still good to receive anchor texts and help you with pagerank.
I think web directories are not so popular today because there are lots of medium to be found on the internet to find what your are looking for like search engines, answering sites, blogs, etc. When it comes to web directories it will only provide you direct traffic from the the visitors.