Early Bird Special
If you want to reward people for signing up early (and helping you fill out your seasons), set up a discount that expires well before your season starts by using the "Expires" field and assign it to your season product in the product manager. Another idea is to use the "Remaining Availability" option to restrict the discount to the first 50 people to sign up. That will create a race to sign up! It's up to you to decide if that's a good thing.
To create a discount that starts at midnight and reward those night-owls, set the "Begins" field to "23:59" the night you want the discount to start. To be especially cruel, set it to expire at 5am.
Create a code for the In-House (host) side only, and assign it to a different product each week. For example, 50% off various items in your food court. Be sure to alert your customers with signage.
Five Days in a Row
To encourage your customers to sign up for camps sequentially, which helps you more efficiently manage them, create a discount using the "Sequential Camp" option. This option really only makes sense for Camps. Set the "Required Quantity" to five (or whatever you like) and you're good to go. If you want to give your customers a discount for signing up for five or more days and you don't care if they're in a row, just set your "Required Quantity" and leave the "Sequential" option turned off.
To give your customers a free donut when they buy a dozen, set the "Required Quantity" to 12, set the discount to the dollar price of one of your donuts and assign the discount to that product.
This discount applies to a customer who signs up a second child within the same family to any program. You can limit it to the same season if you choose.
An example of a shopping cart with an automatic Family/Sibling discount applied. Once the second child in the family is added to the cart, the discount is automatically added to the shopping cart.