The eBay of ERC721 tokens, meet OpenSea
We’re excited to announce the alpha launch of Open Sea — a decentralized marketplace for digital assets on the Ethereum blockchain.
Over the last few months, we’ve seen the emergence of several new digital assets on the Ethereum blockchain. The most prominent of these was cryptokitties, but several more are emerging. Decentraland recently held its initial auction for its LAND asset, and several other Ethereum-based games are in the works. We believe there will be an explosion of these assets in the coming months.
Most excitingly, the community is solidifying a new standard around Ethereum digital assets. The ERC721 token standard provides a common interface for the accounting, transfer, and inspection of non-fungible digital assets.
At Open Sea, we’re excited about the emergence of this new class of digital assets. We believe that “true digital ownership” means that assets will be traded across a diverse ecosystem of decentralized exchange platforms.
We’re building Open Sea as the first of these digital exchanges. 
https://opensea.io/assets
That's really cool that you guys chose to use an ERC721. My company is looking into that as well. Much more advanced and with more capabilities. Definitely an exciting addition to the Ethereum protocol!