The best application for Bitcoin mining --> Central heating
Take away all heaters on the planet and replace them with small inexpensive mining rigs. If you have one in every room, you would be able to generate some Satoshi's and the by product {heat} could be used to warm the house.
I also see a good application in chicken farming in cooler areas. {Chickens are very susceptable to low temperatures, and they die quickly in week 1 to week 4} If these chicken farmers, join forces with Bitcoin mining farms, and they channel the heat to warm the chickens, they already saved some money and reduced their loss.
Or they can simply install these Bitcoin mining bulbs in the huge industrial farms. {For those of you, who do not know... The lights stays on 24/7 in a Chicken farm, to fool the chickens into laying more eggs and to grow them quicker}