your DD, me and Leonardo da Vinci, camdancer (and evidently loads of mumsnetters!!... not to mention, Barack Obama, Prince William, Angelina Jolie, Paul Macartney, Matt Dillon...etc....etc.) 
the only other thing i would add to the below list, is colouring books... there used to be a great shop in Soho in London (not sure if it's still there these days) called the Left Handed Shop, that sold lefthanded cheque books and address books (as well as scissors, measuring jugs, pouring ladles etc), and i suppose colouring books would be the kid version of that. i'm sure you could find them online
the fountain pen thing is a bitch! not only smudging, but u also usually bend the nib by trying to push it across the page.
i did the mirror writing thing for a while apparently...
it's cool to be a leftie... like someone else said - more creative :)