Continuing on the topic of my name...
My name is Jonathan. This is, I believe, the most common spelling of the name. Indeed, I don't know any Jonathan who spells it differently. Once I queried the Cisco employee directory for each spelling. I don't recall the exact split, but it was overwhelmingly in favour of what I consider the correct spelling.
So, given this, why on earth do people constantly get it wrong? This has been happening all my life that I remember. These days I regularly get emails that start "Johnathan" or "Jonathon". Even when in reply to a mail from me. That of course has the name spelt correctly in the From: header. Gah!
With regards to contractions of my name, if you're my friend you can call me Jon (though I will never introduce myself as this). I am not John (yes, I've had emails with this at the beginning). If you know me from a long time ago then you might know me as Jonny. That's fine too, though I tend to find it a bit odd when people who've known me for less than 10 years or so call me it. If you're someone who has just rung me up, asked me my name and been told "Jonathan" you most certainly can not immediately reply by saying "So, Jon...".
No one ever spells Noodles incorrectly, except Socks.