Not for the squeamish, beef tongue, liver, kidney, and heart are common cuts to find in butcher chops, too. Tongue is fatty, usually boiled, and common in many types of cuisines including Mexican, Indian, Portuguese, Brazilian.
Calf livers are considered a delicacy around the world, and can be baked, boiled, broiled, fried, stir-fried, or eaten raw.
Though almost no one eats beef kidneys in the US, they are low in fat and high in protein. Typically, they're used in stews or served rare.
And beef heart was once a common meat for the poor, but because it's so lean and flavorful it's now coming back into the mainstream. It can be simmered, baked, or braised.
Source: Williams-Sonoma