I am a mortgage agent (in Canada), and often place my clients in ING mortgages. Right now their variable rate mortgage is Prime (currently 3%) minus .65%, so today you would pay 2.35%. For a 5 yr term, the rate itself is not guaranteed, but the discount below Prime is guaranteed (so no matter whether the Prime rate goes up or down, you always get .65% off).
Their 5 yr fixed rate is 3.59%, and that rate is applicable no matter what the amortization is (you can take a 5 yr term, but amortize it over 20, 25, 35 yrs, etc). On both the fixed rate and variable rate mortgages they have lump sum pre-payment privileges of up to 25% of the original mortgage balance per year, and you can increase your payment by up to 25% per year as well. Payments are weekly, bi-weekly, semi-monthly, monthly...whatever you want. There are no fees for any of these payment or pre-payment privileges.
Purely out of curiosity, could you explain what ING offers to American consumers? I'd love to know how it differs from the products they offer here.