Our house seems to have evolved a name. It is a very tricky house to find by address alone as it is positioned in such a way that it looks to passers-by like it might belong to either of two different streets, but in fact belongs to a third street, from which it cannot even be seen.
It's slap in the middle of town, though, and is right on the main footpath into the little town center, so everyone has seen it, and it's quite distinctive looking, so everyone knows exactly which house is meant by its description.
So when people ask where we live, I rattle off the address and get blank looks, but when I say 'you know, the blue house' everyone knows. So locally it's just known as 'The Blue House'.
I wouldn't dream of putting that on an official letter though! We do have to have our full address on the wall though because it really is a bugger to find otherwise.