Location, location, location.

Google wants to create a new kind of online advertising where its network knows your precise location and displays ads for businesses within just a few blocks of wherever you are.

That's OK with me. Letting Google tout a deli around the corner seems like a fair trade for getting free WiFi service.

But there's a Big Brother risk in the emerging category of ``location-based services'' that isn't getting enough attention.

Municipal WiFi networks, such as the one Google is proposing, could easily keep records on where users are connecting, and it's easy to imagine ways that information could be misused.

The risk extends to mobile phones, which are also about to become geographically self-aware.

What if a cell phone company signed a contract with a credit bureau to transmit the location of deadbeats who are late on their student loan payments? Or a wireless network operator allows a topless dance club to force ads onto the screen of every notebook computer in the neighborhood?

We, as a society, need to set rules for the road.

The debate needs to start now, because location-based services will start flooding into our lives within the next year.

I'm using Google as an example here only because the Mountain View company is attracting so much attention these days, and because its proposal in San Francisco -- submitted Sept. 30 -- didn't become public until late last week.

Google's existing privacy policy, while it doesn't mention location tracking specifically, is strong enough to prevent the worst-case scenarios I've just mentioned.

But 25 other companies have expressed interest in building or participating in a wireless network in San Francisco, and some of them might not have the same scruples. Or Google could change its mind.

That's why we need laws at the city, state or federal level. It's not enough to rely on corporate good intentions.

In San Francisco, Google is pursuing a ready-fire-aim strategy. The company is offering to first dip into its deep pockets for a network that will cost somewhere in the vicinity of $10 million to build. Then Google will figure out later what new ways of delivering information and ads make sense with citywide WiFi.

Of course, with Google being Google, the company is wrapping its proposal in lofty rhetoric.

``Combining WiFi with Google technology gives us the ability to offer a citywide online access network that will be free to anyone, anywhere, anytime -- clearly the emerging and necessary ideal as humanity continues to cross this great digital divide,'' the company declares in its filing.

I'm not sure free WiFi can end hunger and bring world peace, but it's still a big deal. If nothing else, the spread of free or low-cost muni wireless projects should finally break the monopolistic grip of cable and DSL providers on high-speed Internet pricing.

The proposal includes a vague paragraph on local advertising delivered with ``advanced technology that can target advertisements to specific geographic locations . . . Now, mom and pop local shops will be able to specifically target affordable advertisements to WiFi networks users within a few block radius.''

Google doesn't yet know exactly how this would work, according to spokesman Nate Tyler.

``We want to learn more about how people interact with these kinds of services,'' Tyler said.

I can see lots of applications where local advertising would be welcome. If my car breaks down, for example, I could boot up my laptop and quickly find which gas stations within a half-mile have a mechanic on duty, and then call up a map showing me how to walk there.

Mobile phones that know their locations will save lives, by summoning help when the owners are in trouble and don't know or can't communicate their location.

So it's up to all of us, as citizens and voters, to make sure the good parts of location-based services move forward, and the bad parts don't even get started.