Today with the range of new technical fabric that we have access, we can recreate some physical effect in electronic like sensors with variable resistivity.

1-
Combining good conductor fabric and bad conductor fabric (resistive), you can easily create a pressure sensor.

pressuresensor-01

Some example of tutorial to make this kind of sensors.
Neoprene pressure sensor
http://www.kobakant.at/DIY/?p=65
Neoprene bend sensor
http://www.kobakant.at/DIY/?p=20

2-
When the sensor is made you can plug it into a simple circuit to see is effect on a led or with a multimeter but to increase the possibilities, you can use microcontroller to interface it and read it.

In this class, we will learn to use arduino and more precisely a lilypad (the textile version of arduino.