Dragan, thanks for your detailed reply.
After posting this, I continued thinking about it, and am now quite sure that it is, indeed, a pyramid scheme.
The part that worries me most is that there seem to be several companies (or individuals?) involved, all of them posting large amount of signs all over the city.
I think I am going to gather support for a vampire-hunt. (A vampire is a legendary creature that sucks your blood. If it bytes you, you will become one of them.)
Hilmar.
Difference in opinions hath cost many millions of lives: for instance, whether flesh be bread, or bread be flesh; whether whistling be a vice or a virtue; whether it be better to kiss a post, or throw it into the fire... (from Gulliver's Travels)