JiriH has created this nice squash and stretch ball rig to give beginners an introduction to rig animation. However, note that the rig only works for Blender 2.46 RC and hopefully the final 2.46 release as well.
More and more Blender users are starting to practice animation. As we know professional squash & stretch ball rig is the must to start with. After weeks and weeks of research I am releasing Blender Squash Stretch Ball rig.
I plan to release in depth DVD video tutorial during this summer as well. Hope that release notes are clear, I tried to make a rig very animator friendly and intuitive. Looking forward to your videos :-)