To be clear, I hosted this with WiFi and OS X "Web Sharing," which is actually an Apache server which looks for content in
/Library/WebServer/Documents. So drop Neo Geo in there, turn on Web Sharing, and Bob's your uncle. Or, put it on your Slicehost (etc.) and you can ping it from all over town. (I was hoping to see long/lat vary just when I walked around my living room, but this did not transpire.)
Update: now hosted at http://neo-geo.gilesb.com/. Check it with your iPhone to find out your latitude and longitude.