This is a useful hint if you have a Mac and an iPad (or iPod touch), and you want to share a hotel wireless Internet connection with both devices.
In the System Preferences Bluetooth pane, pair your Mac with your iPad (they don't need to be connected yet, just paired). Then, select the iPad in the list of Bluetooth devices, and click the Advanced button. Check the 'Share my Internet connection with other Bluetooth devices' option. This should switch you to the Network preferences pane and prompt you to create a new Bluetooth PAN device.
Now go to the Sharing preferences pane and select Internet Sharing from the services list. Under 'Share your connection from,' select Airport, and under 'to computers using,' select Bluetooth PAN. Then check the checkbox next to Internet Sharing in the services list to enable Internet sharing.
From the iPad's Settings app in the General pane, tap Bluetooth, and connect to your Mac. In the top left corner, in place of the Wifi signal strength indicator, you should see a pair of interconnected rings indicating that you are connected to your Mac.
When you bring up a new page in Mobile Safari, you might be prompted by the hotel's ISP to select billing options on the iPad; just tap Cancel, and you should be able to browse normally.
[crarko adds: I tested this, and it does work as described. I've used it before with mixed success; sometimes I've had a hard time getting the Bluetooth connection between the MacBook and the iPad to stay up.]
Mac OS X Hints