Neat trick for for loops that sets the iterated variable for you:

for (var i = 0, o; o = all[i]; i++) {
  if(o.href === "bleh")...
}

Same as above, but speed up large loops by not getting the length attribute every time:

for(var i = 0, len = arr.length; obj = arr[i], i < len; i++){
    if(obj.href === 'bleh')...
}

Namespacing and singleton:

// create a namespace
if(typeof(Yourmom) == 'undefined') Yourmom = {};

// now your singletons can be namespaced
Yourmom.bleh = {
  init: function(){
    // do some stuff
  }
};

Equality: if you really wanna check that 2 things are equal, both in value and in type, use the "threequal". Check out Douglas Crockford's "Javascript: The Good Parts" for more.

var a = "something";
var b = "something"
if(a === b) // a & b are equal in value and type

Add load event gracefully:

Yourmom.addLoadEvent = function(f) {
  var old = window.onload
  if (typeof old != 'function') window.onload = f
  else { window.onload = function() { old(); f() }}
}

Yourmom.addLoadEvent(Yourmom.bleh.init)