The basic idea is that we want to help you find and share discounts near you. The video (click 'Watch a Video' on the left) will help explain the concept/history if you're interested.
Our iPhone app's release is pending Apple approval (hopefully just a few more days ...).
HN contributed to this in a very real way. Two years ago when I started visiting HN I had no intention of ever trying my hand at a startup. But being surrounded (at least online ...) by the entrepreneurial spirit here really inspired me.
The Lisp thing isn't actually a selling point - I just thought that the crowd here might find it interesting. If there is demand, I'd be happy to write some blog posts on the how/why of some of our architectural decisions. We're using a 'NoSQL' key-value (with btree indexing) persistence layer too :-D
The lack of real persistence in Redis (up until recently, of course) prevented me from using it. If I were to go with something else - Cassandra seems really interesting (I think I saw a cl-thrift somewhere ...). But, elephant/bdb for now ...
Nothing like having a flat text file on a remote box, good for your sleep at night.
I wasn't familiar with beanstalkd, but it seems interesting. I already have an asynchronous thread-pool based job queue built on the back end that could work well for something like that ...
-Deployment Specifics (libraries, source control, control scripts, etc). This stuff is pretty annoying to figure out on your own - I was lucky enough to learn in person from a great Lisp hacker at a previous job.
Is there anything else you'd be interested in?