First the million dollar homepage, now the million quarter homepage!

Any proof that link farms hurt?
IMHO they don't. They are useless but they don't hurt. Because if they would hurt, that would be a very easy way to shutdown your competitors (not something I would do but surely some would).
BTW, most pixel pages don't have direct links (they use a counter) so they can't be considered as link farms.

 

Actually, some have a single link only, because they market a single pixel only. Such as http://www.you-cant-resist.com. And it works, because people are bursting with nosiness and want to find out where the pixel forwards to.