I have posted about several tools to create PDF files, so today here is a tool to help you manipulate them. PDF Split and Merge is an open source program which does exactly as its name says:
- split your pdf documents (into chapters, single pages, etc.).
- merge many pdf documents or subsections of them.
- extract sections of your document into a single pdf document.
- mix alternate pages taken from two pdf documents in straight or reverse order into a single document.
- rotate pages of the selected pdf documents.
- visually reorder pages of a selected pdf document.
- visually compose a document dragging pages from selected pdf documents.
The program comes in both a basic and enhanced version. This tool in combination with a PDF creator for the most part should accommodate virtually all of your PDF needs.

Jason Faulkner is the man who brings you our daily tips. He is based in Atlanta, Georgia.
For a command-line tool which can do much the same, see PDFTK, e.g.:
http://en.wikipedia.org/wiki/Pdftk