Need to pull pages 2-4 out of PDF, but don't want to spend money on Adobe's Acrobat? Take a look at pdftk, a command line tool for manipulating PDFs.

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.

Other cool tricks can be found in PDF Hacks.