Your title and comments imply that you weren't looking for a sticky footer (stuck to the bottom of the window as content scrolls below it). I assume you were looking for a footer that would be forced to the bottom of the window if the content does not fill the window, and push down to the bottom of the content if the content exceeds the window boundary.
You can accomplish this with the following.
<style>
html,
body {
margin:0;
padding:0;
height:100%;
}
#container {
min-height:100%;
position:relative;
}
#header {
background:#ff0;
padding:10px;
}
#body {
padding:10px;
padding-bottom:60px; /* Height of the footer */
}
#footer {
position:absolute;
bottom:0;
width:100%;
height:60px; /* Height of the footer */
background:#6cf;
}
</style>
<div id="container">
<div id="header">header</div>
<div id="body">body</div>
<div id="footer">footer</div>
</div>
Source: How to keep footers at the bottom of the page
