Making an electronic electroscope
Build it exactly as shown - you have one end of the resistor connected to the gate, then the other end connected to an antenna. The resistor is not required as noted in the text, but it should help protect the FET gate from damage. The length of the antenna is not so important, even without one you should see some sensitivity.  

You can also use a MOSFET or CMOS gate to make this kind of circuit - basically, anything with a very high input impedance will do.  

See this question I recently answered about someone accidentally making one by leaving a microcontroller input floating (it actually has a link to the same circuit)  

Also see this FET input opamp based version by Robert Penfold mentioned in the comments. An another here which shows a breadboard layout.