Related Links of Interest

Hardware and Software:
Finalscratch - hardware-emulated digital scratching
Traktor - a decent DJ program, supports digital scratching (dare to compare :)
MJ Studio - another DJ program, mimics scratching but not very realistic :)
BPM Studio - yet another one, better than the above two but doesnt scratch.
Virtual Turntables - no scratching, but very good mixing and cueing features
AnalogX Scratch - the ONLY other digital scratching engine out there, nice interface

DSP/Sound Related resources:
Guide to Digital Signal Processing - a very nice online book covering DSP
Numerical Recipes in C - yet another excellent book online
Harmony Central - nice resource site for sound programming
Galactic Algorithms - very nice collection of code
Maz-Sound - Samples, software synths, reviews, you name it!

Other cool sites:
Computer Science House - Home of Soundcraft!
Rochester Institute of Technology - Home of Computer Science House :)
123DJ - Online store of nice DJ equipment, decent prices.
Hyperreal - Information site on the underground rave culture
Live365 - Online radio stations