ING Direct doesn't have a strict minimum balance, but will close your account if you use too many "free" services or if you need to much personal support.
"We fire our customers is a colorful way of putting it," said ING Direct's Kuhlmann. "While the banking business says the customer is always right, we're online guys and you can only do business with us in a certain way."
I've not had my account closed despite being a customer for almost 5 years, and I've been everywhere from broke to carrying a modest balance.
It's probably fair to point this out, though: at least ING Direct is highly unlikely to arbitrarily close my account and freeze my funds because they think I ripped someone off on eBay.
"We fire our customers is a colorful way of putting it," said ING Direct's Kuhlmann. "While the banking business says the customer is always right, we're online guys and you can only do business with us in a certain way."
-- "4% interest...why not bank online?" (http://money.cnn.com/2005/10/02/pf/debt/internet_banking/ind...)