Anything that has a conductive circuit is affected. In many cases, an open circuit can be affected as well, depending on the resistance of the break and the strength of the pulse.
Radio/telecomm, modern vehicles, power stations, computers, traffic control, plant controls, possibly generators, etc. If it plugs in or has batteries, it's susceptable.
The only way to protect equipment is to harden it, or keep it in a Faraday cage. Being the only one with a working phone doesn't do you much good, and having the only working car will only last you so long. It's a big threat on a National/Regional scale, but I doubt doing much about it will do any good. Make sure your beans, bullets, and bandages are squared away, and that's your 80% solution with 20% effort.