barlav: You're a prudent guy. Even though I've had broadband for nearly 2 years I still have my trusty USR 56K modem installed. I also keep a free ISP installed for times when the cable is down. In the past I've used Juno and bluelight.
I can't say much good about Juno. Even though I had lots of access numbers I always seemed to have trouble logging on. Bluelight now limits you to 25 free hours per month. That may or may not be sufficient -- depends on how long your cable is out. I also found that I had trouble staying connected with bluelight.
I'm currently using NetZero as a backup ISP. My experience is somewhat limited because cable has been trouble-free for a few months now. Still, NetZero has been okay so far.
NetZero