(cross-post from stackoverflow, sorry)

I'm exploring implementation options in Magento and am wondering if anyone has attempted or found a solution to this scenario...

I would like to be able to setup an order via the Magento backend (add products, set shipping price, etc) then have the customer be able to complete the order by logging into their account and proceeding through the checkout process.

Would be really great if the customer could get an email notification with a link directly to the payment step/checkout.

Is there a public extension that does this or something similar? Is the only option to push the products to a customer's cart then manually notify? Any other approaches on this?