This seems like it would be a bit more tricky to do than if you are working with a "regular" website. How do I raise the PR of my directory site? Or, better yet, is it even worth doing in the first place, or should I just focus my energies and attention totally on maintaining the directory site and let PR work itself out?
Operate your directory like any other website. Go ahead and submit to some of the better Directory of Directories sites and maybe start a blog. The PR will come naturally. Or, you can try to artificially inflate your score and hope you don't get caught. Be sure to submit to the vilesilencer list. It has become the only truly vetted list out there. If your directory doesn't qualify, you should fix it until it does.
Post relevance content and comments to sites with good Page Rank (blogs, forums, groups etc.) Follow all Google's TOS. Create good content -- add value (to your site and others). Frequent updates. Submit to directories, search engines, news group etc. Great keywords -- Use Google Adwords keyword tool Regards, Sabareesh
Think about the directory as a normal website and promote it the way like posting on forums, creating hubs and squidoo lenses, sharing links on other directories and social networking sites etc.
Submit your site to high PR web directories and do some blog commenting with your main keyword. When searching for high PR web directories, make sure the directories have a decent amount of links and have a good domain rank by checking them with SEOmoz or Alexa. For now you can consider the Dmoz,org and world-websites.com and can search for more latter.