Well this new form of attack can actually bankrupt a company.
If I'm not mistaken this attack was discovered / invented buy the guys at pirate bay by exploring the way banks are charging fees for electronic transactions.
Most banks and online processors charge you a fee for each transaction they process.
Some allow you to have 1000 free transactions before start charging, others charge you a fixed amount plus a small percent of the transaction value.
Can you spot the attack ?
Just imagine, you start a campaign against some site or organization who happens to accept donations or some form of online payment.
Assuming the bank charges them 0,30€ for each transaction after the first 1 000.
You and your supporters manage to send 5 000 electronic payments of 0,10€, pretty cheap!
The organization just lost 1050€ and only costs each of you 0,10€
I sure can remember a few companies I would love to see suffering a DDO$ attack!