Very nicely done. I take it this is running on Google App Engine ? (Just a guess, based on the Google Account signup).
No need to market it as just for rural locations. In the UK we have Gumtree for example, which is a serious competitor to Craigslist. While I agree to some extent with the idea of Craigslist's simplicity, I think it is becoming long in the tooth and unwilling to consider new ideas, and it's time for a decent, usable replacement.
Some IP-based geolocation would be nice. And some localization: "yard sale" and "apartment" for example are US terms. But that's nitpicking, which is a good sign :-)