One of my favorite features about ING Direct is the fact that you can create so many savings accounts so easily. It’s a great way to help segregate your savings in a very visually simplistic way. Another great feature about those separate accounts is that they each have their own account number. As you link up accounts via ACH, you can keep things nice and separate. Here’s where the concept of a firewall account comes in.
Firewall Bank Account
A firewall account is an empty, or near empty, bank account that you use as an intermediary between your main accounts and a questionable one. The firewall account is kept in a near empty state so that in the event that the questionable account is compromised or otherwise makes an improper transaction, your main funds are safe.
In my case, I have a PayPal account that I have linked to an ING firewall account. PayPal once had a history of reversing payments, sometimes freezing funds, and even allegedly withdrawing money from bank accounts. I don’t know if those stories are substantiated but the risk was great enough to warrant using a firewall account.
Anyway, this is a great strategy I’ve employed for a couple years now using my ING Direct  account as the firewall because it’s so easy and straightforward to open a new account (after you already have one).