Hi everyone,
I made TimeBank https://timebank.tech , a Fullstack Decentralized Application that lets anyone lock away Ether or ERC20-standard compatible tokens (like those you seen in ICOs)for arbitrary periods of time.
Its backend is entirely on the Ethereum blockchain, 95% of the dev work was the UI and writing the smart contracts.
It doesn't handle any private keys directly, but relies on Injected Web3 (such as via the Metamask Chrome extension) or a local Ethereum node running on localhost:8545, and composes the transactions for the user to sign and broadcast.
Contract source, apparently: https://etherscan.io/address/0x459f90b6e8dc23bbf1ff4c2f22aa2...