Why don't the catalog owners add other catalogs to theirs? It is well known that linking websites with similar content increases the power of those websites in terms of searching. In the light of these facts, the catalogs become more valuable (content wise). Or maybe it is the matter of competition?
yeah, they do add other directories. I really don's see any major reason that why it should not be added, unless the site is un-available or down during the review time.
One reason tends to be that people prefer one way links to recip links; therefore a site doesn't tend to have its link added unless it's asked for.
i like to link to other similar sites, if i cant close a sale id much rather point someone to a site that will help them as this means that they may find me a little usefull and maybe come back naive? maybe but you never know... plus in my case id rather they bought from a nice priovate second hand book dealer than end up at the mega giants amazon Mike