Can anybody suggest the best ways to monetize a directory other than selling listings? I'm thinking that if the listing fee can be replaced by some other form of monetization, then there would be no worries about Google's concern for paid links.

Make your free directory very difficult for users to submit their listings. Then sell them those directory submission services.

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You could always use adsense although webmasters generally dont click. You could also use webmaster specific afiliate programs like seo services, aviva directory has one or hosting deals.

Ya, it is much useless to put adsense on your directory. But if you have a niche directory that would be a different case.

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High Page Rank Sites - Link Partners| Singapore Beauty Spas | Authority Photo Hosting Sites | Authority Sites Blog

sometimes adsense shows irrelevent ads on your site

Alternatively, you could join an affiliate program for directory submission services. While I don't want to sound promotional, I do sincerely believe that the Directory Maximizer affiliate program offers a reasonably good opportunity to monetize visitors to your directory especially since the program offers lifetime commissions off every single user that is referred.

You can go for lobo links or info.visilencer for affiliate programs.

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