The development of Nxt basic features is almost done. Now it's time to decide what an advanced feature will be developed in the first place. Please, vote and comment. A thread about Nxt can be found at
https://bitcointalk.org/index.php?topic=303898.0MessagingStoring messages in the blockchain. The amount will be determined by the length of a message, this money will be destroyed increasing value of all other coins. Such messages can be used as digital contracts because they will be signed with the account key.
Two-phase paymentA payment that must be commited. This should stimulate sellers not to cheat their customers. A payment can't be rolled back and the sender can't get the funds back in any case.
Voting systemA tool that lets to vote on anything. Number of voices is determined by the stake of coins.
Colored coinsA system that tracks ownership of any digital property. More information at
http://bitcoin.stackexchange.com/questions/5695/what-are-colored-coins.
Other (in comments)Add anything that you think is more important.