Alternatively, you can use the Data URI Scheme like so:

  >>> "<h1>Hello, World!</h1>".encode('base64').strip('\n')
  'PGgxPkhlbGxvLCBXb3JsZCE8L2gxPg=='

Paste this into your location bar: data:text/html;base64,PGgxPkhlbGxvLCBXb3JsZCE8L2gxPg==

Works in Chrome 10.0