Site promotion is as important for a directory than for any other regular websites and it pays well to promote to a niche audience.

If you are a web directory owner, then one of the better places to advertise your web directory is Directory Critic. A high traffic niche (web directory) site, specializing in various directory lists.

Mack Hankins of LoboLinks has released some intense stats, for the period he was advertising on DC.

 You can read his analysis here.

DirectoryCritic Advertising Analyzed

And I definitely agree with his conclusion

If you have an eye catching banner and a higher page rank directory you might see an outstanding ROI.