I would like to submit here 2 features which seems to me to be missing in actual in-commerce.
if a visitor have a cart, wether a registered user or a visitor, we store order id in user's cookie (or maybe in user record in DB for logged in users), until cart is emptied (order completed or cart reset).
if a logged user have an incomplete order id, we send a commercial reminder email to user, using a cron agent.
We'd need a new setup value: text for email reminder.
i hope you'll like these new ideas :)