In 2011, there will be a live broadcast of the game on many radio stations around the country. Most all of the sports AM stations will carry this audio live, so depending on where you live you will be able to catch the game. If you are around the Philadelphia area tune to WPEN-AM 950. Post your location for that day and I can give you a local carrier.
In 2012 the Superbowl began to be broadcast on the internet by TV Stations.