I hardly think this is original -- I've been thinking for a while now about the idea of using my own re-usable containers when we are out to any restaurant where there will likely be leftovers to take home. This is usually the case when out for big family dinners. I've never seen anyone doing this and I'm sure it wil get some attention but it just makes sense to me.
Last night we were out at this place and another couple of patrons, who were probably locals, were there to order take-out and I saw they had brought their own large plastic storage bins which the kitchen ladelled food into. The bring-your-own doggy-bag container thing is radical enough but as an extension, I'd also consider this for anytime I do take-out too then, seeing as we bring food (and styrofoam) home a lot. I see this as perhaps being more problematic as chefs use the styrofoam sizes for portion control?