Hi!
As an Arduino noob, i dont know a lot about the sensors, but still they seem to be very interesting stuff. So maybe you could just name some sensors that you know. They should be as simple as possible. Just plug in (with some resistors) and ready to go.
Pressure sensor
Weight sensor
Proximity sensor
Current sensor
Magnetic sensor (hall effect)
Touch sensor
IR remote control sensor (has amplifier and demodulator over conventional IR sensor)
PH sensor
Conductivity sensor.
Colour sensor