More ore less is the success of eBay.com based on word of mouth and PR. But now is it now so new anymore so I think they should develop the seller and buyers model into next step.
Here is a simple idea that will give new fuel for more buzz and PR around eBay.com. Instead of having the old traditional way of selling and buying stuff with money they could take it way back into let people exchange stuff with each other. Like I have this car and I want a motorbike to ride this summer… People can then discuss what is a relevant exchange. It can develop into a lot of different solutions but it will drive traffic and of course if the buyer doesn’t have the motorbike I want he ore she maybe have the money I need (but that’s the next level).

eBay.com got more than 100 million people around the world that is probably billions of things that can be exchange in a year.