Webwork - 5:55 pm on Feb 14, 2011 (gmt 0)
From what I can see the model is viable if the traffic that is targeted/generated is comprised of consumers/vendors=visitors, driven by commercial intent, for whom a directory can aid/serve their search/discovery needs/wants/desires in a unique/valued/value added way.
Now . . traffic . . well . . that's a whole different . . can of worms?
P.S. You just gotta love all the "/" that I use in striving for clarity . . and failing miserably. :)