The fantastic no cost wifi detector NetStumbler program for Windows will discover all the wireless access points around your location, even if the SSID is NOT broadcasted, even if they have passwords or a weak signal. This is perfect for wardriving or even searching for internet cafes.
If you are a Mac user, google for MacStumbler.
You should stop broadcasting your network’s name. If they don’t know the name they would be hard pressed to attempt to connect. Go into the admin menu and turn off the SSID broadcast. Now your access point wont show up in the list of available networks.
This is not a failsafe method of protecting your network it is simply an additional layer of protection. People with advanced skills and tools will still be able to access it given enough time. This will only keep it off of the average persons listing. Of course 90% of users are “average”.
A lot like WPA, you can dictate who and what can connect to your access point. You must create a list of devices, along with their net cards MAC addresses that you want to allow. Then by default all other devices will be refused. This control will likely be found at 192.168.1.1 as well, in the administration section of the configuration.
Wi-Fi security isn’t really all that safe, but if your router is more secure than others, the evil hackers will just likely to move along. Wireless access points don’t have too much in the way of security, and most are set to use WEP encryption to put a password their connections, but WPA which is becoming the de facto standard for wireless a bit harder to break than WEP. To convert to WPA, on your wireless devices admin page,(probably located at 192.168.1.1) change the level of security and make your WPA password to something hard to guess.
You can use a packet sniffer on the network, one like ethereal or wiresquid (shown below). This will shown you packet content(ethereal) and volume (wiresquid) as it flies past and around you through the air. Ethereal is a fantastic tool for those interested in the technical aspects of the network. Wiresquid is just plain interesting!