Hello,
You could also create a campaign, let's say "Smart Shopping" and promote the idea. You can start by creating a mission page where you can tell people about the idea behind the coupon website, and ask for their support. For example you could create badges "I'm a smart Shopper" or something similar, badges that visitors could take and add on their website. In this way you could gain backlinks without actually doing any linkbuilding, you can earn a lot of visibility including in social media, and so on.
Just make sure you mission and arguments are strong, and you coordinate your content marketing efforts in this direction.
For the blog you could even write case studies, or reviews for Extreme Couponing - a reality TV Show.
These are just some ideas you could use. I would also urge you to watch this Mozinar: http://moz.com/webinars/strategic-web-marketing and this great video: http://www.youtube.com/watch?v=u4ZoJKF_VuA for inspiration
And an example of a support page with badges: http://www.protectiamediului.org/sustinere/