There are both hardware and software tools for finding networks. Some are simple, others are engineers' debugging gear whose readouts provide extreme detail -- or too much information, depending on how technically minded you are.

Two inexpensive units aimed at consumers are Smart ID Technology's WiFi Detector WFS-1 ($38 including shipping), and Kensington's WiFi Finder ($39.95), both pocket-sized, battery-powered devices almost small enough to be keychain fobs (about 3 by 2 inches). Press a button, and if they sniff an 802.11a or 802.11g network in the air, they light up a series of LEDs to show the signal's strength. That doesn't guarantee you'll be able to get onto the network if you power up your laptop -- there might be a password or encryption protection on the net -- but walking around with the gadgets until you find a potential hotspot sure beats trying to divine a network with your open laptop on the sidewalk or in a train station. The Smart ID device can online be ordered online from the manufacturer in Singapore, but with directional sensitivity and better detection capabilities, it beats the Kensington WiFi Finder hands down in most reviews, such as this one on SecurityFocus.com.

Wi-Fi Detector
WFS-1

If a flashing LED isn't enough information for you, go to stumbler.net and download the free NetStumbler Wi-Fi sniffing software for your PC, or Mini Stumbler for Pocket PC. There is also a free Mac program from a different developer at MacStumbler.com. If you're lucky enough to have one of the supported Wi-Fi cards, these programs listen for network signals coming in through your laptop's antenna and sniff out all surrounding Wi-Fi nets. Compared to the simplicity of the key fob Wi-Fi detectors, NetStumbler's readout looks like something from the bridge of the USS Enterprise. Don't let your eyes glaze over, though. There are just a few sections of it you need to understand.

The most important field is the column labeled "SSID." As you've probably guessed, those are the network names you'll need to type into your laptop's Wi-Fi configuration panel to try to get online. Next to it is a column labeled "WEP." Unfortunately, a "Yes" in the WEP column means a big "No" to your chances of getting onto that particular network -- it's been locked up with WEP or WPA encryption. A diehard hacker might be able to get online, but you won't.

If you've got a GPS device that plugs into your PC, open NetStumbler's Preferences panel and find the option to set the GPS port. With NetStumbler and GPS both running, you can then walk -- or drive -- around the neighborhood, letting NetStumbler automatically note the latitude and longitude of each network signal it encounters. The netstumbler.com Web site explains how to upload the results into MapQuest to create a map of hotspots in your area.

Hackers have dubbed the practice of traveling around with a laptop running NetStumbler or MacStumbler outfitted with a GPS receiver "wardriving," another nod to Wargames. If you're game, drive around with a wardriving setup (you'll need an external directional antenna mounted to your roof or trunk) -- you will be astonished by how many networks, open and closed, you'll find, especially in metropolitan areas like New York and San Francisco. Antenna kits for wardrivers can be found on many Web sites, such as Jefa Tech's.