I agree that in general these kinds of things don't work. That's why I wrote the extended footnote explaining that I've used this company for 10 years and had 20 friends sign up for it, that none of us have ever been charged any fees, etc. I wouldn't just recommend any random online deal without knowing it worked.

Also, if you know how competitive online ad pricing for banking are, it's easy to understand how the cost to acquire a new customer for ING via advertising is easily > $50. But they're a smart, progressive, company so they're fine paying you directly if you sign up without having to be advertised heavily to.