Generally something "American" like coleslaw, macaroni salad, chocolate chip cookies, corn muffins, etc., that I figure no German guest will be bringing.
It depends. For picnics, it's usually my layered salad and crock pot beans. For some dinners, it's Ina's Sagaponek Corn Pudding (decadent stuff, BTW). For others, it's crock pot stuffing, even if there's no bird involved in the dinner. Yeast rolls because I love playing with yeast dough and everybody knows it. And always cookies. Always cookies.