Yes Since the 80's Underground Shelters have been part of the preppers way of life.
Times have changed since then due to extreme population growth which creates a new scenario in how people will react in a world crisis.If you look at how people will stampede over each other on Black friday for an Ipod on sale then imagine how people will react if we have a X flare which will take out all the power for months or years. Preppers all know this and the general public is catching on to the risk factors of the now new threats such as "The Dollars crash , Solar flares, Black plague re engineered or a EMP strike. Those are just a few new world threats. BunkerMaker.com is quite the interesting website as there is a bit of good information for everyone. Their concept using Underground Shipping Containers and reenforcing them is quite genius and affordable. Take a look at some free energy concepts they have also.