B.R.
What do they do when they come home? Eat a snack? Play video games? Text friends? Go to friends's houses? They simply don't get to do it, not any of it, until the clutter is moved from the front door. The kids that consistantly take their stuff immediately to where it belongs might get extra time or first dibs on something. Or finders keepers and you take something they dumped and they don't get it back until the next day when they don't dump their stuff by the door.
A lot of great ideas have been posted here. I love the back door idea! Do you have one that would work? It doesn't matter if it's a litte inconvenient for them-they're kids.