I got 5,000 miles during the last mileathon for opening a Chase and Key Continental debit card.
The bonuses for purchasing tickets and checking in online are generally only for expensive fares only, but the bonuses for opening credit or debit accounts are nice on top of all other offers like 30,000 for a free credit card and 25,000 for a Chase checking account.
Opening a Continental credit card earns 20 credits, a Continental debit card earns 15. When you register you can see the entire list of credit earning activities and how many credits you need for each mileage threshold. For example 30 credits earns 5,000 miles and 45 credit earns 10,000 miles, etc.
The first purchase on the credit/debit cards must be made by 05/31 for mileathon credit. Most other activities must be done by 06/30 for mileathon credit.