You could also use the project as a light logger, using Python to write the readings to a file, each accompanied by a time stamp. If the readings are written one per line, with a comma between the time and the reading, then you will be able to import it directly into a spreadsheet and produce charts from the data.
You could also use other types of resistive sensor in place of the photoesistor, such as:
- Force sensitive resistor: http://www.adafruit.com/products/166
- Ribbon sensor: http://www.adafruit.com/products/178
About the Author.
As well as contributing lots of tutorials about Raspberry Pi, Arduino and now BeagleBone Black, Simon Monk writes books about open source hardware. You will find his books for sale here at Adafruit.