Yahoo, dmoz and Business.com are all general - singing and dancing things, all with major reasons to avoid.
1. Too expensive (dmoz is free though)
2. 99% of traffic delivered from these will be untargeted. And the remaining 1% is so small it will never convert for the fee you just paid. Eg: Yell and Thomson are built for branding - NOT clickthrough, and the paper versions transfer that thought process onto the web, and thus we have failure of clickthrough. People see branded directories and assume it's a sure money maker, it's not as copycats will always fail.
3. The websites that list with these directories,- are simply checking their listing/s they just bought or obtained, and not interested in 'searching' - just making sure their listing is still visible. My belief is the mass general directory industry is on it's way out, as the only ones starting up new directories either want to make a fast buck, and then promptly disappear from the face of the earth with my money - or companies with a much larger picture in mind.
I will say this though, directories may have a 'branding' service to offer, if they (get the idea right) but expecting 1000's of clicks from these is a big mistake, and in most cases is an expensive one.
Most directories are way to expensive, and even more costly than search engines, which they compete with and is another mistake they make.
I recently asked for my details to be removed from several directories because of the hassle they caused me. Says it all really.
[edited by: Maxnpaddy at 8:55 pm (utc) on Sep. 29, 2007]