Until recently, I hadn't found a really good way to organize the cards I've made other than using a square-shaped basket and stacking them on top of each other. It's a quick doable method, but sometimes they get warped and dusty.
But now, Iris has come out with a "Card Keeper" and I found one at Michael's. Here's what it looks like minus the label on the front:
Open it up and all of your lovelies fit nicely inside. You can also separate your cards using the plastic dividers that come with it, but I found that they took up too much space.