Firefox Extensions: Greasemonkey

// ==UserScript==
// @name           Apple's iTunes 1 billion contest helper
// @namespace      http://www.chrisdolan.net
// @description    Prefill some data in a contest entry form
// @include        https://phobos.apple.com/WebObjects/MZFinance.woa/wa/billionSongAlternateEntryForm*
// @include        http://www.apple.com/itunes/1billion/entryform/
// ==/UserScript==

var focus_field = "7.1.49";
var data = {};
data["7.1.5.3"] = "Chris";
data["7.1.5.7"] = "Dolan";
data["7.1.9"] = "1234 Main St";
data["7.1.17"] = "Madison";
data["7.1.19.0.3"] = "WI";
data["7.1.21.0.3"] = "537XX";
data["7.1.25"] = "United States";
data["7.1.29"] = "608";
data["7.1.31"] = "555-1212";
data["7.1.35"] = "January";
data["7.1.36"] = "1";
data["7.1.37"] = "1970";
data["7.1.41"] = "chris@example.com";
data["7.1.45"] = "chris@example.com";

var form = document.forms[0];
for (var i=0; i<form.elements.length; i++) {
   var e = form.elements[i];
   if (e.name == focus_field)
      e.focus();
   var val = data[e.name];
   if (val == null)
      continue;
   if (e.type == "text") {
      e.value = val;
   } else if (e.type.indexOf("select") == 0) {
      for (var j=0; j<e.options.length; j++)
         if (e.options[j].text == val) {
            e.selectedIndex = j;
            break;
         }
   } else
      alert("failed to set "+e.name+" = "+val);
}