Ok, this is a take on the /AFK command, with an extra addition that prevents abuse. you type /AFK and it marks you as AFK, to prevent users abusing it, have it so that when they move, it auto-removes the AFK tag, and if your AFK for say, 30 mins, it kicks you from the game. This will prevent users being AFK for extended time periods, and prevent users forgeting that their AFK.
I'm in agreement with mack; kick seems unnecessary. [: However an AFK feature would be nice, I've seen a problem with the auto-remove AFK after movement. :b People could easily "abuse" it and spam. Only way that wouldn't be possible is if the notice could be hidden. Other than spam, I'd love to have an AFK feature. I normally do just logout, though. xD
@arb: That wasn't the problem. The problem was with players being online, when it says their AFK. @Mack: The kick was just an idea. @Moo: It could be a major movement, like ten blocks or so, and have a cooldown, like say, five mins. If your AFK every five mins, then just don't come back on.