How do I get a div to float to the bottom of its container?

A way to make it work is the following:

• Float your elements left like normal

• Rotate the parent div 180 degrees using

  -moz-transform:rotate(180deg);
  -webkit-transform:rotate(180deg);
  -o-transform:rotate(180deg);
  -ms-transform:rotate(180deg);
  filter:progid:DXImageTransform.Microsoft.BasicImage(rotation=2);
  

  JSfiddle: http://jsfiddle.net/wcneY/

• Now rotate all the elements that float left (give them a class) 180 degrees to put them straight again. Voila! they float to the bottom.

Set the parent div to position: relative, then the inner div to...

position: absolute; 
bottom: 0;

...and there you go :)