Tinfoil tents  

This post from Bruce Schneier made me laugh - apparently US President Obama has a tinfoil tent - Security Tents.

The US government sets up secure tents for the president and other officials to deal with classified material while traveling abroad.

Even when Obama travels to allied nations, aides quickly set up the security tent -- which has opaque sides and noise-making devices inside -- in a room near his hotel suite. When the president needs to read a classified document or have a sensitive conversation, he ducks into the tent to shield himself from secret video cameras and listening devices.

[...]

Following a several-hundred-page classified manual, the rooms are lined with foil and soundproofed. An interior location, preferably with no windows, is recommended.