Announce: at, a tool to run code later

[cmc]

It's not exactly Cron! It's only for one-shot jobs. But you could have a job 
that does its thing and also schedules the next job- not perfect but works. Not 
sure how cron would best be done yet... couldn't find a solution off the top of 
my head that does not need any intermediary data and is also really fast.