Everybody knows what helium does to your voice, this stuff does the opposite...

Jay Leno: How to Float a Boat on Air video and other Knowledge videos at 5min

Another cool video about one of the coldest liquids achievable by man (or woman)...liquid helium...Zero-Viscosity FTW!
Superfluid: Liquid Helium Phenomenon video and other Science videos at 5min

Just for the sake of getting an idea of exactly how cold this stuff is: (Source)
Oxygen
Boiling Point: -297.4°F (-183.0°C, 90<sup>o</sup>K)
Freezing Point: -361.9°F (-218.8°C, 54<sup>o</sup>K)

Nitrogen
Boiling Point: -320.5°F (-195.8°C, 77<sup>o</sup>K)
Freezing Point: -346.0°F (-210.0°C, 63<sup>o</sup>K)

Hydrogen
Boiling Point: -423.0°F (-252.8°C, 20<sup>o</sup>K)
Freezing Point: -434.5°F (-259.2°C, 14<sup>o</sup>K)

Helium
Boiling Point: -452.1°F (-268.9°C, 4°K)
Freezing Point: -459.7°F (-272.2°C, <1°K)

Absolute Zero = -273.15°C