That story reminds me of something I did for a classical music e-commerce site I was working on. I needed to update the ID3 tags on MP3s and FLACs when the user downloaded an album (I couldn't do it in advance as a batch - arcane nonsensical licensing rules w/ storing digital content).
The problem was that it took too long to modify the files when the user clicked "download" after completing their purchase - they had to wait as the ID3 modifier chugged away doing its thing. So instead of waiting for the user to fill out their CC data and complete the sale, I started updating the ID3 tags as soon as the user put the MP3s into his/her shopping cart and cached the result. It didn't really matter much if the cart got abandoned, but the files were all ready for the customer once they got done checking out if they made the purchase.
The problem was that it took too long to modify the files when the user clicked "download" after completing their purchase - they had to wait as the ID3 modifier chugged away doing its thing. So instead of waiting for the user to fill out their CC data and complete the sale, I started updating the ID3 tags as soon as the user put the MP3s into his/her shopping cart and cached the result. It didn't really matter much if the cart got abandoned, but the files were all ready for the customer once they got done checking out if they made the purchase.