Patch Libraries
Bill Orcutt's Max/MSP Externals, Bomb, Boot Squad, CNMAT MAX Work, Eric Singer's Max Patches, FFTease, IRCAM directory of Max objects, Joshua Goldberg's Max/MSP/NATO page, Listlib by MMyneta, Lobjects by Peter Elsea
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.
Support Site for jMax
Free object libraries such as filters, video integration, ongoing projects.