vjtheory.net
Actually this page about a theory of vjing doesnt seem to be actively maintained, the last articles reaching back to 2009. But anyways vjtheory.net seems to be a good starting point for theoretical research and reading about vjs and their visual works, offering a small collection of interviews with visual performers and texts e.g. about aspects of visual interaction, performing and visual arts as such.
Thus having a far reaching history of predecessors there is a lack of written texts on the philosophies and theories related with VJing and realtime interaction. It is apparent, during workshops and discussions at Festivals and symposia, that practitioners of both VJing and Interactive Installations will quickly move on from problems with the practicalities of production to more complex ideas of how and why the process has, for example, significance for the viewer.
The project vjtheory.net intends to develop a community actively discussing and reflecting on philosophy and theory related with Vjing and realtime interaction. This project and the associated book, aim to bring together work by some of the foremost practitioners and academics in the field.
The makers of vjtheory.net aim to produce a body of work which, for the first time, will address these theoretical issues and place the practices of VJing and Interactive Installation, into a useful context.The website is a growing collection of articles, references and art projects in collaboration with contributors from the book and the growing community.

Yochanan Rauert aka Yochee is working as a VJ in Münster, Germany since 2002 and is the editor and founder of www.visual-society.com