Hoople - 8:58 pm on Jul 12, 2011 (gmt 0)
+1 to cnvi's point. I just made one last month. This was for a niche of a niche within a niche. My directory choice lately has been regional directories that focus on a state/province.
Sometimes a directory isn't called a 'Directory'. It could be a 'Resource List', 'Partners', 'Industry List' or *gasp* the frequently bashed 'Links Page'. In my niche there is one site with over 1,300 'Links' pages. Brainstorm synonyms of directory for more.
My point is to get creative in how you look for them. Most definately a 'think outside the box' type of search. Combining 'add url', 'submit url', 'add site', 'submit site' or 'submit website' with your keywords in searching might be productive too.