Jesse Shanon at Adotas suggests that inventory systems found in video games - Katamari Damasi being the example - can teach us a lesson or two about designing the interactive experience of online shopping carts:
"So imagine if you will a shopping environment where a multitude of branded products exists larger than life and the user’s primary interaction with this environment is acquiring these branded products in a fun and simple way that denotes a "game." After all the products are picked up, the player can then browse through everything in a variety of fun and intuitive categories like size, product segment and price point, and at any time, drop the product into their shopping cart. Now, for the non-gamers out there, this may seem a complicated, roundabout way to go shopping. But from the gamer’s perspective, this is speaking to us on our own terms: fun."
The article also points to Panic.com, a site that uses Ajax to power its drag-and-drop shopping cart interface (image above).