Just finished my first (super basic) dApp -
http://CryptoSpeech.com allows you to submit and store a message (up to 128 characters) in the Ethereum blockchain that will be stored forever. All messages show the address of the user who submitted the message and the time it was submitted. In it's current form, it's kind of like a very primitive version of Twitter on the blockchain. Give it a try
If you're interested in learning more about how the site works, see
http://cryptospeech.com/how-it-works.html which has the Solidity contract code and some examples of how Web3 is used to call/execute functions. There are both Ropsten test network and Mainnet versions of the site, so if you're using MetaMask you can select a different network and it'll load that version.
