Here at my mother-in-law's house in Japan, the one available Wi-Fi signal comes with some intriguing restrictions. It's part of the FON network, a worldwide system of 300,000 hotspots comprised of people who share their Wi-Fi signals. As a "Fonero," you can be either

• a Linus, sharing your signal for free,
• a Bill, charging for access, or
• an Alien, like me, paying FON about $5 for 24-hour blocks of access, a fee the company splits with the Bills.

To become a Linus or Bill, you need to buy and run a Wi-Fi router from FON. But here's the fascinating twist: As a Linus or Bill, you can then use other FON hotspots for free wherever you travel. A mashup with Google Maps shows available hotspots. Here are some in the area of Tokyo where I used to live (click to enlarge):

The hotspot near my mother-in-law's house is flaky. It fades in and out, and the speed at the best times is half of what I get on my mediocre DSL connection in California. Several times a day, it slows waaaay down. When I tried to upload a 3 MB file the other day, YouSendIt estimated that would take 116 hours! I could have flown home and driven the files over to the magazine quicker than that.

But the interesting thing I discovered this time is that services from FON partners Google and Skype are always active, even when you haven't bought Wi-Fi access. That means I can check and send email through Gmail (though not upload attachments), make calls with Google Talk or Skype, check headlines with Google News and Reader, watch Google and YouTube videos, read Blogger sites, explore Google Maps, and more.

Before venturing to a part of Tokyo I hadn't visited before, I planned out my route using Google Maps' Street View. I took a screenshot of the crucial turn, loaded it onto my iPod, and danged if it didn't look familiar when I got there. I spotted the white tree trunk right away, even though it was covered with leaves at this time of year:

So far this month, I've ponied up the access fee to FON just four or five times, when I needed to upload files or check out specific sites outside the Google world. But it's surprising how much you can do inside that world. Often, I can get the info-bite I need just from Google's cache of a site. If I used Google Docs, I might not even have to upload files.

There is a definite walled-garden feeling living inside Google World, though, one where the walls are permeated with tiny windows that let you gaze longingly outside. You get a sense of the digital divide and the challenge of net neutrality, realizing what it means to have a large chunk of the online world inaccessible or hamstrung — and a reminder of how dependent Google is on the rest of the world to feed it.