We used to sing a song when I was in grade school and the chorus was "Jam and jelly, peanut-butter, sliced bananna sandwich!" repeated over and over. Except for the bananas, it always sounded good to me. :-)

Personally, I'm fond of peanut-butter & butter (a bit of sweet cream to balance the salty/savory peanut butter) and a "reeses" - peanut butter and hershey's syrup/nestle quick powder and whipped cream.