Potential Divider :

As the name says, we divide the potential or reduce the voltage in a circuit with help of potential divider.

V out = V in * R2/(R1+R2)

Current Divider:

It is used to redirect current flowing in a circuit.

I out = I in * R1/(R1+R2)

Balanced Wheatstone Bridge

A bridge used to measure resistances

(R1/R2)=(R3/R4)

Voltage Divider Calculators

www.raltron.com/cust/tools/voltage_divider.asp 

www.calculatoredge.com/electronics/voltage%20divide.htm

www.bowdenshobbycircuits.info/r2.htm

www.daycounter.com/Calculators/Voltage-Divider-Calculator.phtml

..