Just a quick bug report: the webserver will crash whenever it receives a request with less than 5 chars due to the string.Substring being used on unchecked data. For example, try telnet <netduino IP> and just hit enter..
Under controlled environments accessed only via a browser this won't be a problem, but if you expose your netduino to the outside world this could be an easy DoS.
I fixed this by changing the initial lines of InterpretRequest to:
string commandData; // Remove GET + Space if (rawData.Length > 5) commandData = rawData.Substring(5, rawData.Length - 5); else return null;