Here is the datasheet for the SoftPot (I am using a 400mm rectilinear, standard variety) http://www.sparkfun.com/datasheets/Sensors/Flex/SoftPot-Datasheet.pdf
Standard resistance for the ones over 300mm is listed as 20Kohm.
Resistance range is from 1kohm to 100kohm.
Resistance tolerance is +/- 20%.
Operating voltage is listed as <10V; the 5V pin is used with Arduino.
Is this the correct linkup for the sensor?
SoftPot Ground (outside pin) to Arduino analog ground
SoftPot Signal (center pin) to Arduino analog input
SoftPot Power (outside pin) to 100k,1/4watt resistor to Arduino 5V pin