Good old days.Sorry to upset you, but this is a very old trick. Previously, bots were specially set up for this, they either created profiles on forums with the target site in the signature, or wrote something on the forum, linking dots to the target site. It is believed that now this does not work, because bots no longer transmit PR through such links.
Wow how technology have changed since that...
I'm talking around 2000's what a good memories