This is uber geeky, and so if that's not your bag, Baby, then you might want to skip this.
I recently had to break down a multi-page PDF file into different PDFs - basically, rearranging the file into logical sections each as its own file. This is neat. This, too.
As you'd expect, there are ways to combine multiple PDF files into a single PDF as well.
We now return you to a less geeky normal blogging schedule.