Good news to all you link builders out there. SEOmoz just updated the PRO SEO Web Directory List. The long overdue update includes over 400 directories (up from 180) separated into three categories – Web, Local and Social.

Wait, aren’t link directories dead?

The practice of obtaining links from online directories has changed dramatically over the past 10 years. The stereotypes of the past are both true and dangerous. Spammy, low quality directories flood the lower cesspools of the Internet. An unbridled strategy of obtaining links from these non-discriminate directories can actually hurt your SEO.

But times have changed, and strategies have become more evolved.

Rethinking Directories

We can move beyond thinking about directories as nothing more than paid links. For webmasters who use this approach, the links they obtain may not be worth the effort. An intelligent directory strategy provides depth to your SEO campaigns and offers tangible benefits including:

• A more diverse link profile
• Qualified referral traffic
• Citations for different vertical ranking algorithms
• Trust/Authority Signals
• … and, of course, the link.

If you use different directories for different purposes, you can achieve this and more.

A. Web Directories

If links were easy for everyone, they would be less valuable for all of us. In general, the lower the bar of entry into any directory, the less inclusion into that directory is valued by the search engines.

Some editorial directories raise the bar by charging a high cost of inclusion (Yahoo, Best of the Web) and being somewhat selective about whom they include. Three hundred dollars is a lot to pay for “inclusion review” but the truth is that for an established business, these links are like bread and butter.

Other directories focus on a particular area, and thus are harder to get into. Examples of these “niche” directories include sites such as:

• Designflavr – CSS / Design Gallery
• Chart Porn – Infographics
• Blog Listing – Blog Directory
• Engineers Edge – Professional Directory
• Donations 4 Charity – Charities

When pursuing directory links, keep the following tips in mind:

1. Not every directory link is right for your site. Be selective and don't go for every link out there.
2. Pace yourself. A good hint I got from Ian Lurie's Fat Free Guide is the 2:1 rule: for every two directory links you build, make sure to build one genuinely natural link. This helps to keep your link profile looking “natural”.
3. Research. Understand where your link will be placed before you go after it. Check Google’s cache of the page to make sure they are indexing it. Large directories are often plagued by bad SEO, and not every link carries the weight it should.
4. Seek relevancy. Ask yourself if this link has the potential to send qualified traffic to your site. Even if it's a small amount of traffic, it's probably worth the effort.

I’d often rather have a hard-to-get link from a smaller niche site that an easy-to-get link from a larger well-known directory.

B. Social Directories

We know that the rise of Social SEO means sharing your content on sites like Facebook and Twitter can have a positive impact on your site’s traffic. But far too many people limit sharing to the big three (Twitter, Facebook and Google+) without considering other social sharing sites. The plethora of specialized social sites offer several benefits.

1. Member Profiles – Here’s a random profile from Mister Wong, a social bookmarking site. (thank you rgonzalo!) Mr. rgonzalo appears to be an authority on the site. Any content he shares will carry weight with the Mister Wong audience.

2. Content Publishing – Instead of a single website listing, social sites allow you to promote individual pieces of content. Using the above example, whenever Rgonzolo shares a URL, that content is likely linked to and noticed by search engines.

3. Increased participation increases visibility. You probably can’t participate in every social site out there. For web marketers, focusing on a few sites where you can devote your time, like Quora or CrunchBase, may be a good strategy. Those who become trusted authorities within their community are often rewarded with increased visibility of the content they share.

C. Local Citation Directories

Using local directories requires a shift in thinking for many webmasters, because it’s not always about the link, but about the citation. As David Mihm points out, the search engine’s local ranking algorithms work much differently than the search algorithms.

For local SEO, search engines trust verifiable information from local portals such as Superpages and Judy’s Book. In most cases, if you are a verified business, gaining a citation from these sources is worth the effort and time.

For more on local SEO directories, I highly recommend reading Mike Blumenthal and Andrew Shotland (and David Mihm, of course.)

Directories = Diversity in Your Link Profile

Just as you shouldn’t rely solely on directory links, you shouldn’t ignore them either. The goal is a diverse and blended link profile. Many webmasters have abandoned directory links due to the bad reputation they have gained over the past years. In truth, the variety and quality of the directories available today offer unique opportunities to expand your SEO reach and diversify your link profile in future-proof ways.

I encourage you to check out the new PRO Directory list, it's an awesome resource. That said, any SEO can take advantage of the tactics in this post. Even with a curated list, using Web directories takes time and research.

There are no shortcuts in link building, but the effort is worth it.