controlP5 is a graphical user interface library for Processing which adds basic controller elements like sliders, buttons, list to a sketch as overlay or in a separate window.
oscP5 is a library that enables Processing to communicate with other hardware and software applications using the OSC protocol.
sDrop adds drag and drop support for files, folders, as well as text and urls to a Processing sketch.
Processing Library Template
The Processing-Library-Template project aims to support Processing library developers with an eclipse project to build Processing libraries. The provided template will compile the library, create a javadoc reference and generate a one page html document.
The template is now part of the Processing project and available through