One of my family's favorite recipes is for a bar cookie that originally was named Special K cookies and was a no bake drop cookie recipe.
It is really simple to fix and takes only about 5 minutes. I renamed the cookie recipe because when my kids were little they could never remember the Special K part of the name so they would just ask me to fix "that peanut butter stuff we like".
Anyway, here is the recipe:

1 c. sugar
1 c. lt. corn syrup
1/8 t. salt

Bring to a boil, stirring constantly. After mixture is at a full boil, continue to cook for 45 seconds, stirring constantly. Do not cook longer than this or bars will become hard as cement. Remove from heat immediately.
Stir in:
1 1/2 c. peanut butter.
When well blended, stir in 4 c. of Rice Krispies cereal, Special K cereal, or whatever grain cereal you have around your kitchen.
Spread the mixture into a wax paper lined 13x9 inch baking pan or just spread out of waxed paper if you like. Let cool for a few minutes and either cut into bars or tear apart into pieces. You can also drop by spoonfuls onto the waxed paper.
This is always a favorite recipe when I have to take something quick for a family dinner or other social gathering.