BOTW (http://botw.org/)
Business.com (http://www.business.com)
DMOZ (http://www.dmoz.org)
DMOZ Resource Zone (http://resource-zone.com/)
DMOZ submission guidelines (http://dmoz.org/add.html)
Gimpsy (http://www.gimpsy.com)
JoeAnt (http://www.joeant.com)
RubberStamped (http://www.rubberstamped.org)
Skaffe (http://www.skaffe.com)
Uncover the Net (http://www.uncoverthenet.com)
Web Beacon (http://www.web-beacon.com)
WoW Directory (http://www.wowdirectory.com)
Yahoo! Directory (http://www.dir.yahoo.com/)
Directories of Directories
Directory Archives (http://www.directoryarchives.com)
ISEDB (http://www.isedb.com/html/Web_Directories/)
Search Engine Guide
(http://www.searchengineguide.com/searchengines.html)

Some Notes

Apply to become an editor at JoeAnt, Skaffe, Web Beacon, and DMOZ in
categories that interest you. DMOZ will probably reject you. When you
do apply to DMOZ, try to apply for a small, ugly, and non-commercial
category (maybe a local one) and take your time filling out the application.

Search beat out directories as a primary means of navigation due to scalability and
efficiency of the search business model. Directories are nowhere near as efficient
at monetizing traffic and generally are not as relevant as search engines.
In addition to search, there are also other forces killing the margins of directories:
• Social news sites. Bottoms-up news sites have virtually no cost and
can quickly build authority because the user becomes the editor, which
means the content is relevant to them and they have a vested interest
in marketing their own work.
• Social bookmarking sites. Similar to social news sites, but users tag
pages they find interesting. There might be some spam marketing
going on in both of these channels, but because we can connect to our
closest friends AND can leverage the user base of the community, we
get a fairly high signal to noise ratio.
• Bloggers. As more and more people maintain websites in active
channels that people are actively paying attention to (i.e., are regularly
reading), it will be easier for engines to determine what parts of the
web are important, and discount those that are not. Quality blogs also
help identify communities and place more context around most links
than most directories do.
A Yahoo! Directory link, listings in a few of the top general directories, and listings
in niche specific directories are still worthwhile because they help identify what
communities you belong to and are signs of editorial quality. But registering in
1,000 directories is not a long-term effective link-building solution. The role of
outlying directories on the web is being reduced as a whole due to so many more
people maintaining active websites.
If competing channels are actively participating in or are actively mentioned in the
active portions of the web then you are going to need to come up with creative
ways for your business to get exposure in those parts of the web as well if you want
to compete.

Some directories have recently been removed from Google’s cache, while others
are not crawled very deeply. Additionally, some of them have not had their cache
dates updated in a great deal of time. Google might be trying to slow the growth
of directories by not counting the links from many of them. Make sure you check
the cache before paying for a listing.
Some of the directories will have a greater effect on relevancy in MSN or Yahoo!
than they do on Google, so even if a directory is not counted by Google, the link
price might still be cheap for its effects on other search relevancy algorithms.
Many directory owners are building multiple related directories. Some search
algorithms such as Google Hilltop are likely to automatically filter out some of the
relevancy score from a second directory if it is easily identifiable as being related to
the first directory.
The one-time listing fees make directories exceptionally appealing, but expect that
many directories will eventually be ignored by some of the search engines. In my
perspective, that cost is factored into the listing prices. I average out the link costs
for links from a number of sites. If I can spend $1,000 and get a dozen or two
dozen well-trusted links, then that is going to be a good buy for launching a site.
The reason there are so many different pieces of information associated with
directories is that for a good period of time, they were pure gold. They provided
cheap and easy marketing and a virtually unlimited ROI, but because they were
getting so abused Google had to buck the trend by coming up with ways to lower
that ROI.
Instead of just discounting some of the links, I believe Google may even place
negative weighting on links from sites they define as low quality. Since Google is
so much more complex and harder to manipulate than Yahoo! and MSN (and
Yahoo! and MSN still place great weight on directories, even on many of the bad
ones), it is hard to explain what directories count as quality links – it really depends
on your brand strategy, short term goals, and long term goals.

I think it is safe to say that when you look at directories such as Yahoo!, DMOZ,
Best of the Web, JoeAnt, and Gimpsy that they probably count as good links in all
the major search engines. Google still ranks many niche sites well, primarily based
on general directory links with few other citations.