I keep re-discovering the same thing about JavaScript: it's deeper and sturdier than its reputation. Because it is mostly used by HTML gurus, and often for small effects, it is easy to see JavaScript as a simple shallow language for adding just a little bit of code to web pages. But it really is a full-featured powerful functional programming language.

Simon brought it home once more with Executing JavaScript on page load, where he uses closures and functions as first class objects to solve a web page modularity problem:

function addLoadEvent(func) {
  var oldonload = window.onload;
  if (typeof window.onload != 'function') {
    window.onload = func;
  } else {
    window.onload = function() {
      oldonload();
      func();
    }
  }
}