Hardware sleep to save battery on AVR-based boards.

Make your Arduino pretend to be a keyboard

Drives stepper motors connected through a step/dir driver board

Text manipulation

Kinda useful functional nodes

Read values from a quadrature rotary encoder (EC11, optical wheel encoders, and others)

Random numbers generation

Nodes to read OneWire DS18B20 digital thermometers

Adafruit Motor Shield V1 communication. The old one based on two L293D and 74HC595 chip. Cloned by many vendors.