There's a really interesting article and discussion over on the EKMPowershop website right now about Coupon Codes and whether having a field to enter a code on your website checkout is a good thing or not?
As Anthony Chesworth says: "Want your customers to feel they are being ripped off or losing out on a deal? Then make sure your online shop has a "Enter Coupon/Discount code" box on your shopping cart or checkout.
Every time I go on to a site that asks if I have a Deal Now I do the same as 90% of other users and go to Google and start searching and alot of the time I end up buying the products elsewhere."
You can follow the discussion here, including links to some more scientific research into the matter.
Personally I think it can be a problem, not least because when I see the field for a coupon I imagine that there must be coupons out there (even if that's erroneous) and it does feel a bit rum to be paying full whack.
What do you think?