in another thread i have seen you could set up an alarm to a specific time with the alarmtool tool. like
alarmtool -a -t 1180873445 -R 86400 -C -1 -d -o -e mplayer mymp3.mp3

It has worked for me, you could setup an alarm to run a programm like mplayer my.mp3 or something or doing a cron job.

It where nice if somebody could write a gui to set some cron jobs to a specific time and we could use our alarm-api as a taskplaner

i have not found a documentation or a howto for using the alarmtool tool ;(