It's a great command. Just type "/afk back at 7:45" and when someone messages you they get an automatic response saying "back at 7:45".
It's an awesome feature, and it builds community? meh, not really, but people feel more welcome if when they message someone they get an automatic response saying, "This user is AFK" than thinking the person may just be ignoring them..
Anyways I brought this up because I just now wanted to go afk, and discovered that there is no /afk command.