We have a binder with those plastic inserts, and our son puts his favorite artwork into it! I will sometimes tell him how much I love something he's drawn, and then he'll run and put it into his binder. I love looking through the binder, and seeing all those memories - and plus, seeing the progression of his drawing skills over the years! Gotta get better about putting dates on his drawings though.

We store the rest of his drawings in a big drawer, and cull them over time...

Where do you store your LO's artwork?