pages2pdf: a shell script for converting a bunch of images (say, scanned pages or transparencies), given in any common format, into a single PDF file. Includees the option of reducing resolution and presenting multiple images per page. See also slides2pdf, an older and somewhat inferior version (which produced these outputs: [1][2][3][4][5]).
rexecsync: a shell script for saving the output of an arbitrary command on a remote computer into a local file, such that on repeated invocations only differences are transferred (requires librsync).