Just discovered the the excellent script.aculo.us drag and drop shopping cart. It is implemented with the script.aculo.us javascript library and ruby on rails. It is a perfect fit for a project I am working on but I needed a PHP version here is the rough first draft with source code.

I can definitely see something like this being the next step in ecommerce sites. No more hitting "Add to Cart" and waiting for the page to refresh, view the cart, then hit "Continue Shopping". Simply drag it in and it pops right up...