PDF Booklet opens a PDF file and creates a new one that can be printed as a booklet.  It has many functions for manipulating the pages of a PDF file.  PDF Booklet can scale the pages so that they can be printed on a different page size. You can adjust the margins, add blank pages and print multiple booklets in one run.

If you wish to create an A5 booklet that is printed on A4 paper and folded PDF Booklet can arrange the pages so that they are printed with the last and first page on the same sheet. It's simple then to fold and staple to produce a booklet.  However if you have a book, with many pages it is necessary to print the pages in smaller folded sections. The program can even adjust the margins to account for creep as the outside sheets of a section have to go around more sheets and need to have slightly larger inside margins and slightly smaller outside margins.

Here is a longer review of the program.