Back on OSX one of my favourite small programs was called PDFCompress, which compressed a large PDF file into something more manageable. There are many ways of doing this on Ubuntu as well, but nothing really as smooth as I used to on OX.
Finally I took the time to figure out how I could make a small shell script based on ghostscript. The whole script looks like this:
gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/default -dNOPAUSE -dQUIET -dBATCH -dDetectDuplicateImages -dCompressFonts=true -r150 -sOutputFile="compress_$@" "$@"
and by saving it in the nautilus scripts directory:
It shows up when I right click on a file. For most of the files I have tried so far today (uncompressed PDF files), it compresses the files to at least 1/10th of the original size. Very useful, particularly when I only need screen resolution for files.