One interesting concept is putting an ebook up on ebay for $5-$7, and putting 100 copies, so that when people buy it, it will be automatically delievered to them. Although I haven't tried this, with the amount of traffic you can get, you can easily make at least 1 sale per day. Has anyone tried this?
Recently, ebay has been overrun with people trying to do exactly that. The problem is that you'll never get $5-$7 for an ebook, because people are selling 100,000 or more in one auction for the same price. I recently bought a pack of 850,000 ebooks, graphics, templates and apps for $7.99, so you'd be hard pressed only selling one for that price.
Such as? I guarantee you that if you sold 1 ebook for $7.99 and I sold 100,000 for $7.99 that I would make more money in the long run.
The best way to leverage ebay is to sell your ebooks for 99 cents and promote affiliate programs in the ebook. Make the ebooks go viral by giving people resale rights to it.