Group discount facility

This is a wishlist item.

We have discussed having group discounts for multiple registrations. This could be done via:
- A code that can be used [n] times
- A code that can be used (or automatically applies) for anyone that registers from a certain domain (i.e., their conference email address is @discount-domain.com)
- A code that applies (automatically) to all registrations from a single person

It doesn't really matter how, but this would be useful. If I could specify, I would ask for the @discount-domain version.