To do your own wardriving, Netstumbler is the de facto application to use. Just download and install, then put your notebook in your car and drive around. It will show you all of the access points that your computer can reach and whether they are encrypted or not. If you really get into this, you may want to map the access points you've found by getting a usb gps device for your notebook (most will work fine), and then upload the saved log to a mapping site, such as WiGLE.Net