HP Touchpad would have been great for this at the $99 price-point if you'd managed to snag one while they still had them. Modern android devices can speak CalDAV beautifully to Zimbra for a couple dollars add-on sync connector. I'd actually been toying with this at home as something to hang on the wall in my kitchen just with the family calendar on it, but haven't been able to justify the price tag for home use yet.

"aCalendar" is a nice full-screen calendar display that'll show the current day or current week. The trick is getting the screen to not go to sleep (and of course you'd have to leave it plugged in).