Automatically, at install time, remove locale info and man pages in languages I don't use.
Sync mail. Automatically install security updates. Check for changes in webbpages I am particularly interested in. Regularly publish texts I am working on (I don't use it right now, but I had my dissertation draft published by cron regularly) or auto-generated reports on the state of different systems (used at work for a database of exams of students).
Ultra fast syncronising of sent, received and deleted mail between the imap server and local maildir caches on all computers I regularly work on.
r-cran-hmisc r-cran-gdata r-cran-gtools
emacs auctex