<div class="container">
  <div class="header">...</div>
  <div class="navigation">...</div>
  <div class="main">...</div>
  <div class="footer">...</div>
</div>

html, body { height:100%; }
.container { min-height:100%; position:relative; }
.main { padding-bottom:50px; }
.footer { padding:10px 0; position:absolute; bottom:0; width:100%; background:#ffffff; height:22px; line-height:22px; }
.ie6 .container { height:100%; zoom:1;}