Don't you hate when you run into a locked down pdf on the web? I search google all the time for title filetype:pdf and some are locked, this is the solution! PDFCrack is a GNU/Linux (other POSIX-compatible systems should work too) tool for recovering passwords and content from PDF-files. It is small, command line driven without external dependencies. The application is Open Source (GPL).
If you want to crack zip file passwords use fcrackzip.fcrackzip is a fast password cracker partly written in assembler. It is able to crack password protected zip files with brute force or dictionary based attacks, optionally testing with unzip its results.
Today, I thought I'd go over a simple shell script that runs on both Linux and Unix (hopefully, pretty much any flavor) to wrap a popular password cracking program called John The Ripper, JTR from here on out, which you can download directly from this page, if you're not already using it.