In common with the tradition at the time, I have two middle names, my father's and godfather's first names, and i never use either of them. I vowed that if our child was a boy, we would not give him 'Andrew' as a middle name - i think it infers that a parent thinks they are important enough to have their name carried on.
I have three girls, so both my christian and surname for this particular branch of Hughes dies out when I peg it.
same reason you have a first and last name, really: to distinguish yourself from other people. Most people don't need them, but it's quite possible that someday Rich Z. Finch will need to make it clear that he's not Rich Q. Finch.
Family historians love the middle name. It was often the case in the Victorian age (and the practice has continued) to give the first-born child (and sometimes the younger children) a middle name that corresponded to the mother's maiden name or, sometimes, the grandmother's maiden name or grandfather's first name. This helps to trace the correct lineage when there are two or more possibilities at first glance.
@andy: Maybe one of your daughters will keep her surname after marrying.
I did and our son also has my surname, which made my parents very happy, since otherwise I would have been the last!
The Harry S Truman & Richard E Grant references reminded me of the classic line from North by Northwest. Cary Grant offers Eva Marie Saint his matchbook. She looks at his name on the back of it:
My dad went to register the birth of my older sister, and got it wrong - her middle name is Isabella instead of Isobel as agreed. My mum wouldn't let my brother and me have them after that.
Following on from my previous post, my dad's middle name was Morton, and when I used to go to horse shows I used to add this to my surname, with a hyphen, to appear posh!
My mother-in-laws middle name was Monteith. I think it was also to do with carrying on a tradition. When my daughter was born, nearly 40 years ago I refused to give her the honours, but now my daughter wishes I had!!! oh well c'est la vie!
My middle name is a love story (not literally!!) - my dad went to register my name in the same as my mum's but my mum hated it so much she changed it so that i have my current name first and it was left as my middle name.....sorry can't bring myself to tell ya wot it is. :O( Lol