Correcting .avi's

I've got a collection of .avi movies that have off-synch audio. Is there any program that can correct the synch?

Use VirtualDub. Write out a .wav file from the .avi, work out how much the synch is off by, adjust the .wav in an audio editor (eg. Audacity), then replace the original audio with the resynched .wav. Fairly easy.