Nice summary of the major decentralization projects:
What this really means is that transactions, identity verification, trust, reputation and payments become quantifiable and programmable.
And it opens up a whole range of possibilities:
Decentralized voting (e.g. Agora), where voters pay using a crypto-currency into an account representing their choice, with the winning candidate being one with highest balance.
Decentralized Domain Name Registration (DNS) (e.g. Namecoin) would be based on a crypto-currency model, and operate independently of ICANN (so technically immune from Internet censorship). Namecoin uses the .bit top-level domain.
Decentralized storage (e.g. Maidsafe and Storj), where trustless nodes would work together (using crypto-currencies as means of payment) to exchange storage space and bandwidth.
Smart self-validating contracts for real-time revenue sharing (e.g. Secure Asset Exchange); helping artists secure and verify their digital artwork by logging it in the block chain (e.g. Monegraph); and even decentralized Twitter-like P2P asynchronous messaging platforms (e.g. BitMessage and Twister).
Document certification (e.g. Proof of Existence) is a clever use of the block chain as a publicly visible and authenticated timestamp.