If you want to have the HN chatroom always at your side when browsing HN... go grab the GreaseMonkey HN toolkit, then copy paste this code at the end of the file, but inside the last IF clause. No warranties expressed or implied. :-)

  var center = document.getElementsByTagName('center')[0];
  var tbl = document.getElementsByTagName('table')[0];
  tbl.setAttribute('width','100%');
  var chat = "<iframe width='100%' height='" + ( window.innerHeight - 20 ) 
  + "px' frameborder='0' scrolling='no' marginheight='0' marginwidth='0' "
  + "allowtransparency='true' src='http://chatterous.com/hnyc/embed/?" 
  + "bgcolor=FFF0DA&titlecolor=FF7800&linecolor=FFB547'></iframe>";
  center.innerHTML = "<table width='85%' cellpadding=0 cellspacing=0"
  + " border=0><tr><td valign='top' width='60%'>" + center.innerHTML 
  + "</td><td valign='top' width='40%'>" + chat + "</td></tr></table>";

(edited for formatting)