What are the Best ethereum DApp ideas that haven't been launched yet?

Ethereum's decentralized and anonymous nature are great for some types of Dapps, such as prediction/betting and stablecoins. However, there are already many players on both these fields (e.g. Augur, Gnosis; Makercoin, Digix).

What do you guys see as great use cases for Ethereum DApps (i.e. an app that would be better on Ethereum that on a normal website) that have not been launched yet?