http://www.quirksmode.org/index.html?/js/cookies.html

Where you find one, you find many

//************************************************
// createCookie
// Borrowed from the internet (Scott Andrew)
//************************************************
function createCookie(name,value,days)
{
   if (days)
   {
      var date = new Date();
      date.setTime(date.getTime()+(days*24*60*60*1000));
      var expires = "; expires="+date.toGMTString();
   }
   else var expires = "";
   //document.cookie = name+"="+value+expires+"; path=/";
   document.cookie = name+"="+value+"; path=/";
}

//************************************************
// readCookie
// Borrowed from the internet
//************************************************
function readCookie(name)
{
   var nameEQ = name + "=";
   var ca = document.cookie.split(';');
   for(var i=0;i < ca.length;i++)
   {
      var c = ca[i];
      while (c.charAt(0)==' ') c = c.substring(1,c.length);
      if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
   }
   return null;
}