This was written because somebody asked me what streaky bacon was, because of my writeup here. Obviously streaky bacon is not as widespread a concept as I thought.
The main difference between streaky and normal (I think it is properly called back) bacon is the shape of the rashers, normal bacon has the characteristic question mark shape, where streaky looks more like a long thin equal sign. The sides of the rasher are more or less parallel.
The second difference is the texture of the bacon, normal bacon has a large area of meat with a rind on one side of it, streaky bacon has, well, "streaks" of fat running down the whole rasher.
Streaky bacon, with its higher fat content is good where you want the bacon to moisten or add flavour to a meat dish - my mum uses streaky bacon on the Christmas turkey. To my taste it is also nicer in any non-sandwich related food, apricots wrapped in bacon is usually streaky bacon, as is little rolled up bits of bacon on cocktail sticks (common at lower class cocktail parties).