how do you let person X across the street know your site exists?Go across the street and tell them about it. Not everyone will sign up and its a slow and painful process, but this is the best way to get to know your users and their needs early on. Ideally you should have iterated the idea before touching a single line of code or design with a group of interested people who not only like the idea or what you're saying but would have been committed to trying it out and actually offering feedback on whether or not the idea is something they would be interested in.
I'll assume the above was never done and you guys went ahead and got the site build out anyway. The best alternative is to reach out to the people around you (like your neighbors directly), as well as communities online that relate to the sort of problem you're aiming to solve (hopefully there is a problem you're solving and not just a solution). Blogs, forums, competing sites, etc... The trick is not to be intrusive and try to offer a compelling solution and get feedback.
is it possible to get publicity and write ups if you don't have funding or famous entrepreneurs at the helm of your project?
Yes but this is not a long term strategy to retain or attract the right set of users needed to get the site up and running. Early on, it is better to get a few users on board during the beta who absolutely loves your product and is willing to grind through it and give you feedback than a bunch of people who half heartedly like your site.
Hope that helps.