These infrared photodiodes are a proven light sensor in BEAM technology.
The CdS is a light sensitive resistor offering a range of 160 ohm to 700k sensitivity.
IR emitter and receiver in one package for close-range optical detection (sold individually)
This SPDT snap lever switch is modifiable into tactile sensors.
Here's a really cool quadrature encoder and motor driver for the GM17 Gear motor designed by the micro-specialists at Didel.