Setting a automator action to run everyday
You can save an automator workflow as a Plugin, and it becomes an actual alarm action available in iCal.

Here's a doc for an older version of Automator.
http://docs.info.apple.com/article.html?path=Automator/1.0/en/ensm2063.html

In Snow Leopard/Lion, when you create a new Automator event you can choose "iCal Alarm"