What I'd like to see is a recursive function that calls itself to
explore every node of a browser's DOM. My idea is to attach a .title
to certain input fields to mark them for special processing, and then
call a generic recursive routine to process every item on the webpage.
Please keep in mind that I prefer a clear and generic example, as I am
mainly asking this question to learn from the answer. Javascript
example preferred, but I can probably adapt a VBA function to
javascript without too much trouble.

I'm a VB/ASP developer that is picking up javascript, so bonus points
if someone can point out the syntax for a javascript equivalent to the
VBA For Each Element In collection structure.

do you want to attach a title to all document elements, or just form elements?

here's how to do both:

function attachToAll() {
  var els = document.getElementsByTagName("*");

  for (var x = 0; x < els.length; x++) {
    els[x].title = "Some title";
  }
}

function attachToFormElements() {
  var forms = document.forms;

  for (var x = 0; x < forms.length; x++) {
    var els = forms[x].elements;

    for (var y = 0; y < els.length; y++) {
      els[y].title = "Some title";
    }
  }
}

// uncomment the one you want to run...
//window.onload = attachToAll;
//window.onload = attachToFormElements;


additionally, you can make "attachToFormElements" more specific by
checking for a certain input type to attach to, or a certain css class
etc

the construct for enumerating object properties is as such:

var doc = document;

for (prop in doc) {
  alert( prop + " = " + doc[prop] );
}