If you are new to Ethereum like I, you might find this information helpful.
What is a Dapp?
DApp is an abbreviated form for decentralized application.
A DApp has its backend code running on a decentralized peer-to-peer network. Contrast this with an app where the backend code is running on centralized servers.
You can find a list of Dapp's that are Live, Demo, Work in Progress or simply a concept at this address:
https://dapps.ethercasts.com/