BarCampLondon3 is of a session on voluntary payments as a business model, and how it can help creators make money from the long tail using the Internet as a distribution channel - donations, tips, free downloads with people paying only what they think something is worth, the experiments by band Radiohead (who in late 2007 released their "In Rainbows" album initially on a voluntary payment basis, with both financial and chart success); writer Stephen King's online downloads experiment with electronic serialisation of "The Plant"; touching on the Creative Commons movement, etc.
The session was by Reinier Zwitserloot. (He's involved with Tipit.to). Again I've embedded the slides underneath to make the video easier to follow.
Personally, I have to say I'm rather sceptical of the pure "voluntary payment" business model. I'd agree with those who feel that that sort of model would only work properly (in terms of decent returns for the "selling" creator, provider or publisher), in relatively affluent and stable economies. I suppose in that context it's worth considering as a possible way to monetise the long tail, the huge numbers of niche products or services which individually appeal only to narrow interests.
But I'm doubtful that creators can make much money in tougher economic conditions. People from poorer societies who can barely afford the basic fundamentals of living - food, water, shelter - are unlikely to voluntarily pay for something which is available for free; why pay if they don't have to, if they need the money for something where they do have to pay?
I also agree that where the "voluntary" payment is to be made more publicly, e.g. taking something from a basket and leaving the money for it in a place where others can see who is or isn't leaving money (as opposed to a download in the privacy of their own home), there will be a degree of social pressure on "takers" to pay.
I'm a Creative Commons fan myself (and this blog's contents are licensed under CC), but it isn't strictly a "free" or even "voluntary payment" business model - free for private non-commercial use only, and strictly commercial exploiters have to pay, not just pay only if they want to. Still, I know many creatives don't believe in CC in terms of their making a living, and think that it only helps increase exposure for people who are already famous. We shall see how things develop...