This is a Vertical Axis Wind Turbine which uses wind energy to drive things like air and water pumps for cooling, irrigation and similar, or an alternator/generator for producing electricity.
Note: this tutorial is also available at http://solarflower.org/tutorial.php?lang=en&tut=vawt with a slightly more usable layout.
The turbine uses the 35-40% mechanically efficient Lenz2 lift+drag design. It is made entirely from scrap materials except for the bolts and pop rivets, and should cost about $15-$30 for the six vane version, which can be made by two people in six hours without much effort.
The three vane version has been successfully survival tested to 80 km/h sustained winds and the six vane version to 105 km. Both will do more, but exactly how much has not yet been ascertained.
Full power curves have yet to be calculated for this particular build, but according to Mr Ed Lenz's calculator (http://windstuff.org/calc/calc.php) a six vane at 0.93 meters diameter and 1.1 meters high with a 90% efficient alternator should produce at least 135 watts of electricity in a 30 km/h wind, and 1.05 kilowatts at 60 km/h.
The materials listed in this tutorial are to make the three vane version. Double everything except the bike wheel for six vanes.