>As to click tracking, have you seen any evidence other than the redirection URLs?
Only that if they are, and those popular site must come from somewhere, that time spent on the site after the click is not a factor. There are plenty of 404's and password protected sites in the directory that are holding position.
Just got a new site listed through Biz-Ex a few weeks ago, and while I can't say conclusively that it is click throughs that are bumping the ranking ( I do the keyword search and click on the listing now and then ) I don't have another explanation. I went from #78 up to the mid 40's and still climbing. Almost all searches are performed using the same browser which is cookied by YAHOO, but with different IP's as I am on a dialup connection. Get people to do a keyword search on your site, click on the listing and it should help to bump it up in the rankings. If ya make it in the top 20 or so, then real search click throughs ought to keep it high, and if not then it can be manufactured.