Look at the page rank of the directory itself... if it's high means they may have many visitors... so it may refer some traffic to your site.

As for your own Page Rank....... I don't think it will help much as Google may not put much emphasis on links in directories.

Furthermore, the directories themselves may not even really "vote" for your site.... the link to your site are "NON-VOTING" links (because, i think most of the directory scripts put the rel="nofollow" attribute to the links.... which Google will NOT put into consideration in ranking your site)......... to make sure, you'll have to check the individual directories yourself.

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