I made a couple of tutorials on Renoise.
In one I cover the basics, in the other I dive in the 09xy, Ex and B0/1 command to fuck up a loop.
Hopefully they’ll be useful.
Basics: http://www.youtube.com/watch?v=qTAPifosHr8
How to fuck things up: http://www.youtube.com/watch?v=OMlDOHoG3N8