pdftk

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
* Apply a Background Watermark or a Foreground Stamp
* Report on PDF Metrics such as Metadata, Bookmarks, and Page Labels
* Update PDF Metadata
* Attach Files to PDF Pages or the PDF Document
* Unpack PDF Attachments
* Burst a PDF Document into Single Pages
* Uncompress and Re-Compress Page Streams
* Repair Corrupted PDF (Where Possible)

Pdftk allows you to manipulate PDF easily and freely. It does not require Acrobat, and it runs on Windows, Linux, Mac OS X, FreeBSD and Solaris.

Last release was version 1.4.1 on November 28, 2006.

Stable, working. Could use a more 'posix' interface and should probably be updated to use poppler.

EDIT: Unable to attempt contact. After jumping through 3-4 contact links I got a SQL error.

EDIT: Author contacted. He seems satisfied with the state of his application. I think it's getting buggier as time goes on... or as adobe changes pdf (it certainly isn't great at fixing pdf problems).