These are various pieces of code, large and small, which I've written and which you might find useful.

• annotate_pdf.py, a python program which adds a small amount of text to every page of a PDF. An example use might be to mark the publication location and date of a paper you've downloaded, or to mark a paper as do-not-cite-or-distribute. here is a very simple PDF, and this is the result of annotating it with a string.
• find_big_files.py, a simple Python script to find where your disk space is being eaten up. It prints out any file or directory whose size exceeds some threshold (0.5 GB by default), not counting any children that are themselves big. It also prints out slack space used. Does not work for Windows.
• Loop LaTeX, a shell script to run LaTeX/BibTeX as many times as needed to process a texfile.
• Pa_arg, a syntax extension for Objective CAML to aid in writing command-line arguments
• SoundScriber, a tool for helping to transcribe audio
• whereami, a simple Perl script to work out the true location of the current directory, resolving soft links and mount points.
• Zymake, a tool for running experiments. Zymake scripts look like shell scripts but have the semantics of a Makefile. Unlike make, zymake treats filenames as sets of key-value pairs rather than strings, allowing for easy specification of experiments exploring many combinatorial details. Zymake is a simple computational workflow management system.