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.
Well - that's enough for me. I'll write up some real blog posts on architecture in the coming days.
But the short version is nginx reverse proxy into hunchentoot, with elephant (and a BerkeleyDB datastore).
Edi Weitz's html-template for html (I personally love cl-who/parenscript, but I could imagine working with front end devs who don't know Lisp - and it seemed like it might be easier for them this way). The HTML is basically purely static - and everything is pulled in with AJAX (well, technically JSON, not XML). I've done some fun things to hunchentoot's sessions so they are completely stateless and, in the future, I could imagine just moving the entire site (html, css, js, etc) to some fast static file CDN, and just load balancing asynchronous API requests across a few Lisp servers. But that's a ways down the line ...