Sensor inputs include:
photocell to measure light
proximity to detect nearby objects
touch 
potentiometer
heartbeat detector
moisture detector
motion detector
​
Outputs include:
LED
buzzer
servo motor
continuous motor

Internal functions which work with battery or USB power, no computer needed:

An Input connected to the A port controls an output connected to the S port

The analog input on A will affect the frequency of a speaker connected to SPACE and Ground.
An input on the L port will control a servo motor connected to the F port
An input on the Up port will control and output on the Down port
An input on the H port will control an output on the I port
Touching the Click port will control an output on the Left and Right ports.

External functions send keystrokes to the computer and include:​

A heartbeat sensor connected to the K port will send a "b" key to Scratch for every detected heartbeat, after a startup stabilization period of about 20 seconds
Touching the Click port will send a "c" key to Scratch
A sensor on the W port will send a keystroke of O when activated and P when deactivated
A sensor on the D port will send a keystroke of U when activated and I when deactivated