One million pixels for sell. You can select an arbitrary block within free ones and buy it, the purchased block will be registered with a smart contract and will be associated with the your Ethereum account. Bought block is yours over lifetime, or until you decide to sell it. You can place a banner on the owned block, assign URL to it and gain traffic to your website while it's in your ownership. Also, as the number of free pixels decreases, the price of one pixel becomes higher. So you can profitably sell your block later. Price for one pixel will be grow every 100 000 sold pixels.