Has anyone attempted to create functionality like this based on a location such as a zip code?

Simon labeled search as The Holy Grail in a blog post at simon.getk2.org and it is a very interesting subject. Please tell us more of what you have in mind and its intended use.

Rather it be for a real estate website or just a company website that has multiple locations. It would be nice when using K2 to be able to have a radius search feature based on a location.