Bitcoin is great, but it misses one thing that usual bank transfers have: payment title.

Perhaps it should be possible to include short (<=512 bytes) message for each transaction.
The message could be encrypted with public/private keys so only the receiver can see its contents.

What do You think ?

PS.
I might be wrong, but the messages could also be used to increase randomness of hashing process by the way, couldn't they ? If not, never mind.