Cycling'74:Makers of Max, MSP, and pluggo.
Composing Interactive Music: Max textbook covering interface design, interaction concepts, controllers, algorithms, and program structure.
jMax Official: IRCAM's visual programming environment for building interactive real-time music and multimedia applications.
jMax user's guide: By CCRMA: The Stanford University Center for Computer Research in Music and Acoustics.
Max Object Gallery: Max objects developed for a variety of installation and performance pieces, with emphasis on device interface.
Max Resource Guide: Links to hardware, software and human resources.
Snot Wong's Max/MSP Creations: Various fun and somewhat useful max/msp patches for you to play around with.