I am going to mention a radio frequency of an emergency broadcast radio station in a post apocalyptic video game (I'm part of the dev team), and I would like to make a reference to real world radio. Are there any historically (or currently) famous radio frequencies?
The International Amateur Radio Union (IARU) has established a small set of emergency frequencies. Some of these are global and some are for one of the three IARU regions. The IARU calls these frequencies "emergency centres of activity".
The full list is here:
By far the most common one is 14.300 MHz. That is monitored in the US by the Maritime Mobile Service Network (http://mmsn.org/).
For your game, if you need global broadcast, I'd use one of the global frequencies. If it is more local, use one of the regional frequencies that are around 3xxx kHz (80 m band) or 7xxx kHz (40 m band). 80m is good at nightime, 40m at daytime. Either one is regional, covering something like most of California.
The regions (http://www.iaru.org/regions.html) are:
IARU Region 1: Europe, Africa, Middle East and Northern Asia
IARU Region 2: The Americas
IARU Region 3: Asia-Pacific
There are other frequencies for non-amateur use, mostly marine and aircraft. The primary marine distress frequency was 2182 kHz, but the US Coast Guard stopped monitoring that in 2013. Marine distress traffic now digital to satellites with GPS data.
This is a good list of those frequencies.
If you want a US-oriented throwback flavor, I'd go with the CONELRAD frequencies from the Cold War era. In case of a major attack, AM broadcast stations would shut down, with only specific stations on either 640 or 1240 kHz continuing to broadcast. Those frequencies were marked with a triangle-in-circle icon on radio dials.