I coded up a HipChat bot in < 100 lines of CoffeeScript. It leverages the existing module system to make plugin writing hilariously easy:

  if msg[0] == '!'
    [cmd, args...] = msg.slice(1).split(' ')
    require("commands/#{cmd}").exec(chat, args)

Just add a coffee file to the commands directory and export an `exec` function which callc `chat.reply` -- couldn't be easier!