Matt is a huge proponent of WordPress and regularly contributes to the WordPress community. He is the author of several popular themes and plugins, and has made substantial contributions to the official WordPress Codex.
Q&A for WordPress developers and administrators
Q&A for professional and enthusiast programmers
Q&A for professional system and network administrators
Q&A for Ubuntu users and developers
Q&A for power users of Apple hardware and software
Q&A for professional graphic designers and non-designers trying to do their own graphic design