If PDF is electronic paper, then pdftk is an electronic staple-remover, hole-punch, binder, secret-decoder-ring, and X-Ray-glasses. Pdftk is a simple tool for doing everyday things with PDF documents. Keep one in the top drawer of your desktop and use it to:

• Merge PDF Documents
• Split PDF Pages into a New Document
• Rotate PDF Pages or Documents
• Decrypt Input as Necessary (Password Required)
• Encrypt Output as Desired
• Fill PDF Forms with FDF Data or XFDF Data and/or Flatten Forms
• Burst a PDF Document into Single Pages
• ..

The nice thing is that one can use it all from the commandline :-).

• Examples Merge Two or More PDFs into a New Document

 pdftk 1.pdf 2.pdf 3.pdf cat output 123.pdf

• Split Select Pages from Multiple PDFs into a New Document

 pdftk A=one.pdf B=two.pdf cat A1-7 B1-5 A8 output combined.pdf

• Burst a Single PDF Document into Single Pages and Report its Data to doc_data.txt pdftk mydoc.pdf burst.