Peanut butter is a great addition to many foods you wouldn't expect. The sweet and saltiness accents spicy or savory foods really well.
If I need something quick and cheap, I'll throw a spoon-full in some instant noodles (use less water or strain them so when you stir it in it doesn't get too watered down) for a pretty damn tasty meal. I prefer kimchi flavored but I expect chicken and most of the other flavors would suit just fine.
When I was a kid I used to put it on my pizza all the time. Plain cheese or pepperoni seemed to suit best. Strong flavor that wont be overwhelmed by the PB.