Shopify Digital Products

It's perfect for our DIY kits, since we can attach a digital download of the instructions that fulfills when we send the customer the physical kit, but it doesn't mark the order as fulfilled until the physical componant is sent.
It also gives the option to automatically send out updated downloads to customers who have already bought the item, which is very helpful.
The only thing I wish was different was that you could reuse the same file on multiple variants or listings, it's a little annoying that it brekas them up and you have to re-upload for each one.