I'd love to see a tutorial covering all the normal render passes for example ambient (even though there is already one) , beauty, reflections, shadows and dof (particularly this one) . We have a tutorial on that topic called render layers in production, it's by Izzy who works in broadcast and it's really good for getting an insight into post work. It was done in Maya 8.5 so a few buttons have been moved but I followed it just fine in 2011, it also uses After Effects but it demonstrates the principle so any post app works. The final part of this tutorial covers zdepth pass for dof in post specifically as well. For relight in Nuke that honestdom mentioned have a look at this, it's very impressive, I think they create magic at the foundry Relight for Nuke - A quick tour (HQ) - YouTube