Free Shipping using coupon

I know this has been asked before—but has anyone come up with a solution for this? Ideally I'd like to be able to have a user use a coupon that gives them a discount, plus free shipping.

I exploited the hole in the system before by giving a coupon code that wasn't in the system, changing the message to "Your coupon was used for free shipping" and voila, the shipping was taken off. Not perfect, but it did the trick for awhile.

However, I'd really like to be able to use an actual coupon code for this.

I'm willing to pay!