Playground - PCMAudio. Playground - InterfacingWithHardware. DigitalWriteFast, digitalReadFast, pinModeFast etc. DigitalWriteFast, digitalReadFast, pinModeFast etc.
This is an addition to the library that greatly speeds up reading and writing to the digital pins using the familiar pin number syntax. One of the strengths of the Arduino is the low barrier to getting started for beginners. the simple syntax of digitalWrite, pinMode, and digitalRead is a big contributor to the simplicity.