Things I don't want to run out of:
Flour
Sugar
Baking Soda/Powder
Eggs
Milk
Crisco
Rice
Pasta (buy LOADS of it when on sale)
Baby Carrots
PEPSI
and my weird one; Top ramen. My kids love them for snacking after school; buy by the case when they are on sale.
I like to cook from scratch so I consider these basic must have items. I can use up whatever meat and veggie I've got and come up with SOMETHING for dinner. I check these every time I shop and try to have one of each in reserve all the time.
The pepsi I try not to run out of so I don't take it out on my family when I'm in withdrawal.