Party leaders, ever get tired of waiting for that one person who is too far away, or someone who is lost? Well how about sending a magical note to remotely invite a player to a party, or send a blasting call that automatically brings your scattered party to you? The idea behind the Horn of Calling would be to make party management a bit easier. Either by offering a way to collect the entire team at the leader's location, or adding a method of remotely adding people to the party. Perhaps even adding a new way to look for a group, by sending out a call that searches for other people with the same quest and asks them if they would like to join a party for said quest.

The first has been suggested many times before (a way to bring party members to you), and there are already /commands to invite people to a party over a distance that just don't work yet.

As for the second thing, /region channel works just fine if you're looking for someone to help you out with a quest.