The 4-Directional Tilt Sensor is a perfect accelerometer replacement in those applications which may not need precise angular feedback.
This type of sensor is commonly used in many smart phones and digital cameras as a cheaper means to adjust the screen display when the device is rotated.

Small 6-pin DIP packaging with breadboard-friendly 0.1in pin spacing
Easy communication with any microcontroller
Positional feedback in four directions
Power requirement: 3 to 5.5Vdc
Communication: 2-pin high/low output for four sensor states
Dimensions: 10.7 x 8.1 x 12.4mm
Operating temperature range: 0 to +50°C

Parallax offer an extensive range of sensor, communication and interface modules for the experimenter working on robotic systems. Most are supplied with extensive documentation making them ideal for use in education. Further information and tutorials are available from the Parallax website: http://learn.parallax.com/