Just the other day a co-worker of mine wondered if there was a way to have Entourage (she's using 2008) automatically archive messages like Outlook does (we run Exchange on the job, which stores all your messages on the server; you run the risk of going over your quota if you don't archive things to a local mail store from time to time). I had to report that Entourage does not automatically archive (though it really should), and sadly I knew of no other automatic solution for her.
I now have a much better answer for her: Entourage Exchange Accounts Optimizer 1.0. It gives Entourage (2004 or 2008) the auto-archiving features that should be built in. You launch EEAO and tell it how old messages should be before they are archived, where to archive said messages to, and if you want it to run on a schedule. That's it.
Entourage Exchange Accounts Optimizer costs $10, though a free demo is available.