Ever work in retail? I did quite a while ago! "Go Backs" were a big part of it - anything behind the register that needed to 'go back' to its place - returns, items customers didn't want, etc. I'm sure you know of this system, but have you ever used it at home?
I have a small basket in our living room I use for little things that get left around, BUT, when my kids' stuff gets excessive, they both get a bin, I fill it up and then we work together to put it away (I do most of it for my youngest!).
My favorite things to use as temporary bins are foldable crates - I have a few from both Green Made (InstaCrate) and Clever Made (Clever Crate) (bought at Sam's Club and Costco). See how they fold totally up in that second pic? I usually keep them in the car for groceries, shopping, etc.! They store easily without taking up much room, are stackable and have lids.
Do you have a "go back" bin you use at home? What about a foldable crate? (HIGHLY recommend!)