This just lobbed into one of our sites from 69.71.222.nnn / CIDR 69.71.128.0/17
It had a blank user agent and supplies a referrer in this form:
http:// www. sitedossier. com/site/www. example.com
(link deliberately broken with spaces)
Did not request robots.txt, took the index page and left.
There is not much of any use about it in Google, but does appear to have been around for a couple of years.