No need to waste time on those non-indexed directories . BTW you will get better response if you post this in link development section .
my main source traffic are from google, yahoo, msn . They are the top3 traffic source. I never looking for information from directory websites.
directory submission surely helps, you can try our any submission service and see what happens, your link popularity will increase. More than your site will be indexed.
The directories and their pages get indexed eventually, if its free its worth a shot, the backlinks help.
They may not be indexed presently by Google, but they may in the future, and they may be indexed by non-US search engines. Remember, Google is not the dominate search engine across the entire world - I know they use different SEs in Africa, Southeast Asia, etc.