I just had this discussion with Corey a while ago.
Directories will RARELY get you any traffic (that too if you are in some featured spot). The main people who actually go through directories are SEO guys looking to place their links on site's of the niche they are working on.
Great traffic from directories...I don't think so.
Directories may have some beneficial effects:
-High profile directories may give you a back link (but in most cases, these are useless back links, even from DMOZ)
-You may get spammers from low profile directories, thus increasing your hit count ;) (Ok, was that beneficial?)