Hi Matt,
If you're in the UK, go to
http://uk2.net and check out their free 56k modem dial-up service. Apart from the local-rate phone call, which will be charged by your telephone operator, the ISP bit is free - they don't even ask you to register with them
If you're not in the UK, then, as Brain_Damage said, you'll need to check what's available in your region.
Hope that helps
Jakeyeager - when the mains power goes down in the UK, the phone lines still work so anyone with a laptop and a dial-up modem can still get 56k modem access through their phone line for as long as their laptop battery lasts