Ether has just launched and offers people the chance to market and sell “pay per call” services. Ether lets you create an Ether Phone number, and set a rate for which people can call on a pay per call basis. It comes with the ability to sell digital content again at a price set by the seller. Ether takes a 15% margin.
I also think it would be interesting to see variation models where marketeers could potentially sponsor an Ether call, enabling a free or discounted service. This could be provided by first surveying the caller, and serving up some relevant advertising.