I have read that getting your site listed in the open directory (DMOZ) can significantly help boost your site's ranking in major search engines. Is this an 'old webmaster's tale' or does it really help?
We did this (listed in DMOZ) for Stack Overflow, Server Fault and Super User.
Since then, I have noticed that the DMOZ text for Stack Overflow appears in a bunch of places.
Open Directory Sites (1-5 of 5)
Stack Overflow - A language-independent collaboratively edited question and answer site for programmers.
-- https://stackoverflow.com/ Reference: Ask an Expert: Computers and Technology (1)
And I specifically note that our Google result summary is that exact text
A language-independent collaboratively edited question and answer site for programmers.
So I'd vote "yes", it is picked up by a bunch of directories still -- and Google.
It's a good idea, but be prepared for a frustrating process.
From the perspective of a web site submitter, once a site has been submitted, it goes into a mysterious black hole. The only way to know that anything has happened with the submission is if it shows up in the DMOZ index, and that can take years. The submitter agonizes over this during the months after the submission. He wonders: Did I submit the site properly? Was there a technical issue with the submission form? Did some technical glitch occur after that? Did some human error occur in the process? Did it get lost in the shuffle? Did the topic editor die? Is he just sitting on a backlog of submissions? Was it rejected for some specific reason? If so, what was that reason? I know I could fix it if only I knew what the problem was! Was the site approved but somehow after that it got lost in the shuffle? Was there some other kind of technical glitch that caused it to get lost even after approval? And so on. The point is that if the site never appears in DMOZ, anyone who submits a site can only see a future of daily checking DMOZ and then sadly realizing that the site still isn't there. But maybe, just maybe, it will be there tomorrow.
I got into a long conversation with DMOZ editors in the DMOZ forums recently, and was surprised at their lack of interest in improving process. For them, it's just a hobby, and that's all it will ever be, until it finally (and mercifully) dies from irrelevance.
The DMOZ home page has a page rank of 8/10, and even sub-sub-sub-sub-categories still have decent page rank.
So getting a DMOZ link is definitely a good idea. One link on its own will only make a small difference, but like Jeff said, it is still used by many other sites too.