This is what cornell.edu uses to redirect people to the mobile site. Lord. Have. Mercy.

cornell.edu.redirect.OLD.js

// Redirect to m.cornell.edu for smart phones.
// (We allow an override of the redirect with a certain parameter.)
var CUhomepage = {};
CUhomepage.ua = navigator.userAgent.toLowerCase();
CUhomepage.params = location.search.toLowerCase();
CUhomepage.mobileURL = "http://m.cornell.edu";
CUhomepage.goMobile = false;
// Detect iPhone and iTouch.
if ((CUhomepage.ua.indexOf("iphone") > -1) || (CUhomepage.ua.indexOf("itouch") > -1)) {
	CUhomepage.goMobile = true;
}
// Detect Android phone (and not tablet; only works if tablet removes "mobile" from user agent string.
if ((CUhomepage.ua.indexOf("android") > -1) && (CUhomepage.ua.indexOf("mobile") > -1)) {
	CUhomepage.goMobile = true;
}
// Override the redirect via parameter specification.
if (CUhomepage.params.indexOf("overridemobile") > -1) {
	CUhomepage.goMobile = false;
}
if (CUhomepage.goMobile) {
	window.location = CUhomepage.mobileURL;
}

cornell.edu.redirect.REVISED.js

var Redirector = {
  redirect: function(){
    window.location = "http://m.cornell.edu";
  },
  present: function(str, search){
    return str.indexOf(search) > -1;
  }
  notOverridden: function(params){
    return Redirector.present(params, "overridemobile");
  },
  isIphone: function(agent){
    return Redirector.present(params, "iphone") ||
      Redirector.present(params, "itouch");
  },
  isAndroid: function(agent){
    return Redirector.present(params, "android") ||
      Redirector.present(params, "mobile");
  },
  isMobile: function(agent){
    return Redirector.isIphone(agent) || Redirector.isAndroid(agent);
  },
  shouldSwitchToMobile: function(agent, params){
    return Redirector.isMobile(agent) && Redirector.notOverridden(params);
  }
};

if(Redirector.shouldSwitchToMobile(
    navigator.userAgent.toLowerCase(),
    location.search.toLowerCase()
  )) {
  Redirector.redirect();
}