Here are a bunch of Wiring Libraries that I've either created or modified over the years.
The libraries are found on GitHub and are mirrored to BitBucket.
Produces square wave tones on arbitrary pins.
Produces PWM signals on arbitrary pins.
Variable color depth version of the LPD8806 library.
A timer library for working with millis(), providing for an easy way to have a recurring action.
Rogue Robotics MP3 module library.
Rogue Robotics SD module library.
Originally written by Alexander Brevig, I updated (some would say I "bloated" it) the library to have a bunch of more functionality.
All of these libraries, and all of my development with Wiring (and Arduino), are labours of love. Please donate!