Not a billion dollar idea, but I think a viable business. We need an Instacart-type delivery of seforim and Judaica. It can be an independent service that is connected to a local retailer, and they deliver till late at night within an hour or two.
I would use it all the time, even with a delivery fee, and I'm sure in today's Shipt/Prime/Instacart society, it would get a decent stream of orders in big frum areas.