I just received an email from ING Direct on their upcoming promotion. You can get 1% cash back from June 1st to July 31, 2007 when you use your Electric Orange MasterCard Debit Card to make a signature-based purchase. Here's the promotional page. Cash back is limited to a total of $500 during this period.
Note, it sounded like you would be using this as a credit card, but it still seems to be a debit card even without the PIN. Here's how ING explains it.
Looks like ING Direct is taking a page from Emigrant Direct credit card which offers 1.4% cash back. With so many credit cards offering 1% to 5% cash back, even Emigrant Direct's cash back credit card wasn't that great. So I don't expect this new promotion from ING to create much excitement. Perhaps if it were 5%, it would have been interesting.
For more info on the Electric Orange Checking Account, please see this post.