Adult friend finder gold
The source IP addresses collected can even provide pinpoint street locations for attacks.
Anyone can register for free, like most dating sites.
However, much the same way metadata collection provides insight to the NSA, this type of information provides attackers with plenty of leverage that can be used against the public.
Spear phishing becomes a lot easier when attackers not only have an email address, but also location, language, and race.
In this case, the administrator would have had two opportunities to notice the abnormality: 1) At the database level, as the data was extracted.
2) At the webserver level, where an abnormal amount of traffic would be sent to a specific address.