A simple chat Ethereum Smart Contract to demo purpose
The Smart Contract is on the Ropsten Network at this address : https://ropsten.etherscan.io/address/0x093fb362b84eca8b6222dc5f34738b062f4ca903
The chat is online here : http://simple-chat-ethereum-v2.s3-website-eu-west-1.amazonaws.com/
Just use Metamask https://metamask.io/#how-it-works and try it.