What have been the most useful resources for you when learning to make RPM's?

If you want a guide that cuts through the noise, I recommend these

Creating RPM's for Linux

JBoss 5.1.0A RPM Spec

But you should keep the Fedora guide bookmarked, as you'll be coming back to it.

I also found Maximum RPM: Taking the Red Hat Package Manager to the Limit very useful as a reference.

Tip: If you're building RPMs on Centos, this link gets your build environment set up nice and quickly:

Set Up an RPM Build Environment under CentOS

The thing that helped me the most was looking at source rpms. Install the source rpm for the smallest app you can find, and look at its spec file.

Fedora packaging guide was useful too, but very heavy on doing things right, to the point doing it at all got a little lost in the noise.

I keep hearing good things about this one... runs