With hurricanes in the news, it's worth noting that many of the states that often have natural disasters (such as hurricanes in the south and earthquakes in the west) will have permanent rules about sales and use tax exemptions for building materials, construction work and other related goods. If you unfortunately find yourself in the terrible position of having to spending money after such a disaster, check to see if there's an exemption. If the exemption doesn't exist, the government may create one so watch for the opportunity of refunds or credits, or consider timing your purchase to when the exemption is available.
And if you're a seller of such goods and services, make sure you handle the taxation of your customers properly.
And I hope this entry is never relevent for you.