Try the cronjob package. It was designed for running reports on the odd schedules set by managers. One downside is that if the server isn't running when a cron was scheduled, it will not run later on. But you can login at any time and run any of your defined crons. It will run just as if it had been scheduled.
If you just provide and sql statement to run, it will format the result as an html table and email the result. Otherwise, you can run any tcl code as well.
