@mislav I figured out the problem. `Host` doesn't show up in `Request.Header` but in `Request.Host`. See the comment for `Request.Host`:

> // The host on which the URL is sought.
>        // Per RFC 2616, this is either the value of the Host: header
>        // or the host name given in the URL itself.
>        // It may be of the form "host:port".

A modification of the example gets this to work: http://play.golang.org/p/DEFLb7_WRJ.

![screen shot 2014-04-01 at 7 14 18 pm](https://cloud.githubusercontent.com/assets/169064/2586837/87a11dcc-ba0c-11e3-8ad5-9fcab4d410bf.png)

`req.Header.Add("Host", "example.com")` still doesn't work...