I always want to send a client more than just a digital file with any work I produce. Below is an example of a box I made for a wedding I shot recently. It contained a handmade box, a personal note, 100+ 6x4" prints, and two USB's carrying black and white as well as colour edits of all pictures edited. Every event is different but something like this is a common occurrence when I deliver photos.
Here is an email from the client the above box was for: