Here is a list of all of the sensors and components as well as a reference code, descriptive use, and a link to purchase (WARNING the internet is a dynamic document, links become outdated. If you happen upon a broken link, please be a kind spirit and modify the link)
LED (Light Emitting Diode) are components that generate light when voltage is applied to them
A Photoresistor is a sensor that detects the level of light and produces a reading relative to the amount of light applied
Temperature Sensor (Sparkfun)
A sensor that detects the surrounding temperature and reports back a raw reading. The data it reports back needs to be modified in order to convert to the desired scale
Temperature Probe (DS18B20)
A mysterious sensor has appeared!