PDFsam is a free open source tool to split and merge pdf documents. It's very simple, stable and completely free.
http://www.pdfsam.org/?page_id=32
Watch video How can I merge PDF files into one file online without registration, duration hours minute second in high quality. This video was added by user asksy 10 March 2012, don't forget to share it with your friends and acquaintances, it has been viewed on our site 388 once and liked it 1 people.