I should do this more often. Look at the wealth of information returned in the headers:

1) They're using nginx (which is powered by Ponies!) 2) The site is fronted by varnish with a ttl of 1 hour, of which there appear to be at least 4 varnish servers. 3) Links to the various CSS files. Do browsers actually use these headers instead of the <link>s in the html? 4) Drupal is somewhere in the mix. 5) Mention one of the company core values, of which there are at least 8. 6) Anyone geeky enough to be reading this should apply for a job.

  $ lwp-request -e -d  www.zappos.com
  200 OK
  Cache-Control: max-age=2452
  Connection: close
  Connection: Transfer-Encoding
  Date: Thu, 02 Feb 2012 23:53:38 GMT
  Server: nginx/1.1.14
  Content-Type: text/html; charset=utf-8
  Client-Date: Thu, 02 Feb 2012 23:53:39 GMT
  Client-Peer: 203.206.129.48:80
  Client-Response-Num: 1
  Client-Transfer-Encoding: chunked
  Link: </favicon.ico>; rel="shortcut icon"; type="image/ico"
  Link: </styles/main.p.20120201135153.css>; media="screen"; rel="stylesheet"; type="text/css"
  Link: </css/print.20120115152845.css>; media="print"; rel="stylesheet"; type="text/css"
  Link: </styles/home.p.20120201135153.css>; media="screen"; rel="stylesheet"; type="text/css"
  Link: </>; rel="canonical"
  Title: Shoes, Clothing, and More | Zappos.com
  X-Cache-Hits: 117
  X-Core-Value: 8. Do More With Less
  X-Meta-Description: Free shipping BOTH ways on shoes, clothing, and more! 365-day return policy, over 1000 brands, 24/7 friendly customer service. 1-800-927-7671
  X-Meta-Keywords: index, zappos, zeta, clothing, shoes
  X-Powered-By: Ponies!
  X-Recruiting: If you're reading this, maybe you should be working at Zappos instead.  Check out jobs.zappos.com
  X-UUID: 970dff52-4df6-11e1-a3ab-001a645b7cf4
  X-Varnish: 1001890813 1001890584
  X-Varnish-Host: varnish04.zappos.net
  X-Varnish-ID: drupal
  X-Varnish-TTL: 60m