Well, I'm actually going to promote a web-directory myself soon... I'm still working on it. And as far as the promotion goes I use a good SEO for all the pages in my directory and although not yet launched I already recieve some traffic from search engines. After I launch the directory I will submit it to a few directories that are worthy, like DMOZ and local directories (that can be specific directories in your case I guess), I'm also planning on creating a little buzz through blog posts, contest, twitter and other social media - just to get it go, and I'll probably buy some cheap targeted traffic or exchange banners, for starters. I wonder how it go for you actually... any advices from this thread you used? cause i was interested to find out myself some useful tips... but it's all the usual...
You can make some reciprocal links with your members and you should sign your directory in some directories for web directory