Coupon websites are great to bring in business, and I found they actually convert fairly well for the customer. you can also do aff marketing directly from the website almost like a shopping cart. One of the nice things about Wordpress is you can create a coupon with photoshop or piccasa, and add some text, and you have a coupon post. I would recommend using some besides default templates.

If you are adventurous, I would suggest something like Couponpress or the Templatic daily deals...