In recent days many link directories have lost their page rank. It is assumed that Google is penalizing them for having paid links. In my opinion many directories exist for only one reason and that is to farm links. Link farms were appearing higher in the Google rankings and in many cases were just a waste of time and effort.
Directories that are created purely to sell links or get rankings are not worth joining. Having said that, I know that industry specific Directories can be good for a business, yet directories without any useful content are doomed to failure.
Links back to your website are important but here's the thing, having links from paid directories with no ties to your business are a waste of time. A site dedicated to Linux was penalized for having paid for links to casinos and adult content sites. I am sure you will agree that those have no relevance to Linux.
I bet everyone is wondering what a good link is.
Links from industry specific sites are good.
Links from blogs dealing with the subject at hand.
Links sites with authoritative and relevant content
Links from sites that do not link to link farms and questionable sites
Links in Blog Rolls.
Links you have not paid for.
So the thing here is when you ask someone to link to you, check their credentials. If the majority of sites linking to you link to questionable sites, you will not get credit for those links. In fact you may even get penalized. You are known for the company you keep.
Some of the largest directories on the net have just learned that the hard way. They are not even appearing at the top of the list when searching for their brands. Directories that are feeling the pain include; Aviva. Alive, Big Web Links, ewebpages, Directory Dump, Elegant Directory and many more.
Another place to stay away from are the Free For All (FFA) directories, they give you no benefit whatssoever because they are link farms that the search Engines do not approve of. Before trying the short cuts, rather write an authoritative article and submit it to ezines and other sites that desire good content.