They also let users send virtual gifts to one another for really low prices.

'gifts' being 64x64px icons that have been curated by Facebook staff.

Actually - someone pointed out to me recently that a 64x64px flower lasts a whole lot longer than a chocolate bar.

The question is which provides greater value to you while it lasts.

...not to mention a lot longer than a real flower, which will wilt, die, dessicate, and crumble into dust.

I think they worked better when Facebook offered them free to promote things. There were a lot of Dark Knight icons being passed around when the movie came out. I don't know any friend that's actually bought one.

Free to users != free to promoters; they surely profited off of those Dark Knight icons.

That's what I meant. I think that's a better ad/gift model than their idea of making users pay for digital icons.