I think that this might be called tethering. Is it possible to connect to your mobile phone (not necessarily an iPhone) via Bluetooth or WiFi and use it as a "modem" to connect to the Internet vie 3G network.? Actually I am pretty sure that Bluetooth won't work. I have seen that "WiFi modems" can be used with the iPad. In principal your mobile phone should be able to do the same thing without needing another 3G account. Does a WiFi modem operate differently in some way?