The more I think about Peerapps (used to be Peermessage, for everyone out there confused about the difference between Peerapps and Peermessage) the more stoked I am.
For instance, this one:
http://cointelegraph.com/news/113579/coinspark-open-sources-a-paypal-like-messaging-feature-for-coinspark
With messaging using Peerapps, this could be "easily added", right?
Another very interesting technology is Ricardian contracts (http://iang.org/papers/ricardian_contract.html) which basically put is human-and-machine-readable contracts. Open Transactions uses them and so does Open Bazaar.
Since a Ricardian contracts is a message, we could publish Ricardian contracts, send them to one-another and enter into binding agreements. If these contracts were published on #channels that people are listening to, we could even get trading going using them and it would be totally decentralized.
I don't remember whether or not Peercoin has "this time locked feature", but this feature could be used to create Ricardian contracts with expiration dates and so forth and so on.
Powerful stuff this Peerapp tech. :-*