Looks well polished. Try to let business owners upload their own offers, that will make it easier for you; instead of hunting for bargains or waiting for users, you can just buy a mailing database and do a blast to those who care (or scrape the contact emails from Google Local, like I did.)
Also, try to define "bon's" somewhere; does it stand for bonus or coupon? The tag line could explain "shop. save. share <whatever it is we're sharing>"
One more thing, spill the beans on the architecture ;-) what do you have behind nginx? Hunchentoot? The html source doesn't look like cl-who, it has comments, perhaps a template system of sorts.
I already have most of your site's functionality somewhere in my private repo, and I am sure many people do too. It's a pity we all have to write it from scratch.
Cheers and good luck! :-)