Although most people think about Bluetooth in its "cable replacement" uses, such as with wireless audio headsets and keyboards, the Bluetooth standard defines a range of protocols and profiles optimized for specific uses. One of the most useful is the Personal Area Networking (PAN) profile, which encapsulates network-layer traffic, such as IP. This means you can use PAN to set up a cheap network access point over a Bluetooth adapter — the bandwidth will not be up to 802.11 speeds but it does offer some interesting properties, such as being invisible to wardrivers in the parking lot, and enabling Internet access on mobile devices without WiFi. To set up PAN on your Linux machine, start with a Bluetooth adapter and a working kernel.

More information at: Linux.com