I saw this on another blog, and I wish I could give credit, but I can't find the link now. As soon as I saw it, I knew it would be a great idea for us.
We drink protein shakes every day, either for breakfast or after a workout. They're not too time consuming to make, but when you add up the time each of us spends every day making one, then washing the blender, it's a bit wasteful.
So I started making them in bulk, and freezing them. But the touch that makes this idea really genius is using these Ball freezer containers. They're freezer safe, bpa free, and perfect for transporting and drinking. I wouldn't lay one sideways, they're not that leak proof, but they fit fine in the car cup holder.
The only drawback I've found is that they don't use the same outer threads that the glass jars use, so I can't use my awesome cuppow drinking lid w them.