These links point to some useful VJ resources around the net:
Virtual Dub Batch Assistant - A batch processing add-on for the free clip processing software Virtual Dub
SleepyTom's Codec Comparison Page - Sleepytom is the expert when it comes to codecs. His codec comparison page lets you see what stuff looks like in all the different codecs.
Channel 4 pixNmix - The pixNmix website at Channel 4 has lots of useful info for VJs including the masterclasses which show several ways of using VJamm in live performances.
VJCentral - Probably the most authoratative website for comparing VJ kit and software
VJForums - The central place where the world's VJs tend to meet and talk about stuff