Newer directories are changing with the times. They are now designed as search engine friendly, making it easier for search engines to crawl and index them. Directory pages are showing up in search results. Many directories are also branching out, including information along with links to other sites. A good example is friskall.com. It is search engine friendly, easy to navigate and also includes articles as well as links to other sites. Inclusion to friskall isn't guaranteed, all submissions are human approved to ensure only quality sites are listed.
Having listings in certain directories can certainly help drive traffic to your site. As web 2.0 evolves, I think we'll see greater importance placed on directory listings.