We have enhanced our older V2 addon with a couple of new features and re-released it for V4.
The Mystery Coupon addon allows you to use a URL that will pre-load a coupon for the customer to use when they go to checkout. Alternatively, you can supply a product_code and that product will be automatically added to the cart along with the coupon.
You can also specify what landing page you want the user to land at after the coupon request is processed. If no landing page is specified (index.php is the default), then the user will be taken to the checkout page.
A couple of enhancements have been added for V4 that offer more flexibility. If more than one coupon code is specified (comma separated list) then one of those codes will be randomly selected for use.
Also, a new checkbox is available to prevent users from 'discount shopping'. The “use once” checkbox will prevent any additional use of the mystery coupon link in the current user session. If a user attempts to use the mystery-coupon again, they will see a message that the mystery-coupon is already in use.
Documentation can be found here.
And the product detail page is here.
Please note that there is NOT a V3 version of this addon available.
Don't forget to check out our EZ Checkout Summary Fields addon for holiday gift wrapping, gift cards and other order information that you can customize for your needs.