title: How do I install from a local cache with pip?
body: <p>I install a lot of the same packages in different <a href="http://virtualenv.openplans.org/">virtualenv</a> environments. Is there a way that I can download a package once and then have <a href="http://pip.openplans.org/">pip</a> install from a local cache? </p>
  
  <p>This would reduce download bandwidth and time.</p>