I disagree:

I built a "grocery list" app that I can access from my phone. If I'm buying groceries, and I update the list, someone else can view the up-to-date list and won't buy a second carton of milk.

Dry erasable markers work fine on white fridges. Don't ask how I know.

At least use a paper calendar -- the whiteboard can get erased if someone/something rubs against it.

This is why we need a smart whiteboard, so we can see the history of what was written on it, and undo accidental erasing/drawing. Maybe even connect it to my butt with a companion app so you can see your whiteboard notes on the go, or share them to facebook/twitter/instagram.

(...Hopefully the sarcasm is obvious).