Dave, most driveways crack over time since most of them aren't poured with expansion joints. And most slabs have cracks in them. Called stress cracks. Caused by different cure rates in the concrete. They're not a problem unless they continue to enlarge or go from one side of the house to the other. If they become over something like 3/16ths of an inch then I would keep an eye on them. There are many areas of the country in which houses have doors that won't open until it rains. Water the foundation as described in the other post. Sprinklers do not suffice to provide proper watering because you need to expand the soil back towards the foundation. However, people with automatic sprinkler systems have less foundations problems, generally, than those that water with moveable sprinklers. It's because the yard is watered regularly. Of course, if your house is built on sand, this doesn't apply.