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
Something I need to do quite often is concatenate (join) several PDF documents into one document. This can quite trivially be achieved with the following from the commandline:
$ pdftk 01.pdf 02.pdf cat output all_together_now.pdf
Above we concatenated 01.pdf and 02.pdf to form the new combined all_together_now.pdf document.