One thing I would love to see in Horizons is some sort of system so that a player could leave personal messages for another who is offline. Maybe even in some form of roleplay context like sending mail. I find myself constantly wanting to leave messages to friends who I have little other way of contacting (they don't read boards, I don't know their e-mail, etc.) about, for example, the leftover metal I have in a silo that they can use. It would be really great if some sort of system could be set up to facilitate this, but I imagine it would be a huge effort and therefore low priority. Still, in a community-based game such as this, it would be nice to see. :)
-Your friendly neighborhood stripey dragon