In 2006 I was asked to do a visual overhaul of the messaging application Gaim, which would later turn into the Pidgin project. Pidgin is a widely used chat application that connects to AIM, MSN, Yahoo, and many more chat networks all at once.
The icon set follows the Tango icon style guidelines for Open Source applications. The complete set consists of over 200 emoticons and objects, and is used as the default emoticon set in Pidgin to this day.
Other than just visual changes, I worked with the Pidgin developers to streamline and simplify the application's interface. We made some design decisions that were controversial back then, but are considered commonplace in messaging applications today.
The main theme of this work was to the shift the focus in the interface away from the underlying communication technology and towards people and conversations. We went about this by finding a set of common behaviours across the different messaging protocols; unifying them where possible, and specialising where needed.