Pressure cookers work best with what would otherwise be long-cooking foods: beans, roasts, etc. Foods cook at higher temps under pressure so cooking times (and fuel consumption) can be greatly reduced.

Unless otherwise specified, recipes use 10lbs of pressure.

dry beans

Dry beans can be covered with sufficient water and cooked for ~30 minutes at 10lbs. This results in a firm bean that can be reheated a few times without breaking down.

heat oil in bottom of pressure cooker

add chilis, onions, black pepper, etc, brown to taste

add rinsed dry beans

bring to 10lbs pressure and hold for 30mins.  
Remove from heat and allow to cool. 

potatoes

wash and cube potatoes

place in steamer/colander

add water for steam, about to bottom of steamer

process at 10lbs for ~7mins
remove from heat and allow to cool

sterile water

Water can be sterilized (for first aid, etc) by processing under 10lbs pressure for 10mins.