RU is down for good, but its being re-started under a new name (which I won't post and won't respond to if you PM me except by reporting you). I too will not respond to requests for a URL, since Quiky and company have made it clear that it is against the rules here to "fish for the fish site", especially if your post count is low.
Glad to see that RU has risen from the ashes after some infighting behind the scenes with the guys running it.
p.s. Quiky, the most recent PM I got about it, the guy said he found it through a google search. Not sure if there is way to turn off certain phrases in google analytics, but it might be worth doing since it kind of looks like people found this site by searching via Google for "Racing Underground invite" or "fish site address" or something.