Mine

alias afk {
  if ($away == $false) {
    set %reason $$?="Reason?"
    nick AwayNick
    away  1  %reason
    /timer 1 0 /amsg  [» I am now AFK «» Reason: %reason «» Left at: $time(HH:nntt)GMT «]
  }
}

alias back { 
  if ($me == AwayNick) {
    nick MainNick
    away
    /timer 1 0 /amsg  [» I am now back «» Reason: %reason «» I was away for: $duration($awaytime) «]
  }
}