Update: James recently posted the XML for a new command that makes decent use of DuckDuckGo to provide answers to basic questions.
It uses the RoboBrowser plugin for VoxCommando, some regex magic, and TTS. See:
http://voxcommando.com/forum/index.php?topic=789.msg9800#msg9800.
As always with commands that rely on third-party websites, if the website changes radically the command may break (or at least the regex may need to be updated to respond to the changes).
We used this just the other night to impress a guest, who posed the question: "How far away is the sun?"