Fastclick is an Able2Know advertiser. The page with the appended link does not exist. But neither does the page:
http://www.able2know.com/forums/viewtopic.php?t=11738&start=0&postdays=0&postorder=asc&highlight=Fastclick
That is the URL for this thread. The only page that really exists as a file is "viewtopic.php".
So basically that is an example of variable being passed to a dynamic code through the URL.
In the case of all the threads here the information about which topic, post, page or even what words to highlight are passed through the browser.
In the case of Fastclick it is an intersital. That URL displays an advertisement for 10 seconds (it gives the option to click a link and skip it) before redirecting to the target link and the target link is the variable being passed to the fastclick link.
So it's nothing on your computer. It's simply a variable (the external URL) being passed to a redirection url. It's done through Javascript and is not on your end.
In what you describe something must have gone wrong and there was a point of failure (probably in the redirect).
This whole intersital thing makes about 40 cents a day and sounds like a pain in the butt. It doubles the possible points of failure for a webpage because in addition to the original page being offline if the redirection URL fails the page fails to load as well,
So I'll remove it in a few minutes. It certainly isn't worth 40 cents a day and was more fun to play with on a technical level than it was valuable as a advertising medium. In the future I will be using a similar technique to allow members to rank the offsite links and possibly comment on them as well.
I'll be reducing the prevalence of the other image based advertisements as well from the forums.
I gave them a trial and I think the Google ads are much more discreet and worthwhile.