My friend Tom used to volunteer on a steam railway. He was stewarding on a steam service on day, and came across a chap holding a bit of paper out of the window. On questioning, it turned out that this chap collected a smut from every steam service he travelled on, and organised them in an album...
Actually, I can sort of understand the feeling of completing a set of numbers, but then I organise a tube of Smarties into colours.
And anyway, talk about casting the first stone, from a forum with a thread entitled "Cutlery Lust"...