A place for WvW people to hang out. I'm thinking that all players that has spent a certain amount of hours in WvW.. or are a certain rank would have access to this lobby.
The lobby would be connected to servers, allowing team chat to function and allowing players to tick out participation without taking spot on WvW maps.
In the lobby we would have bank, trading post, crafting stations and an arena (So you can test your build against others from same server without needing to jump into PvP).
Meaning that you don't have to worry about PvP-builds and leaving WvW when you have participation.
Also.. if alliance system will be put in, this could be an additional map for guilds to recruit veteran players that don't yet have a guild.