I think I wrote my first story when I was around nine. And, looking back, I still think it's the definitive Popeye On The Moon story of its age! And I'll always remember my Superman story with fondness, if for no other reason that it was then that I learned to spell the word "unconscious."
* WARNING * This contains spoilers for the "Master" audio
(if you're not familiar with it, you can find a synopsis at the "Master" entry at the Doctor Who Reference Guide)
(I'd written this before the season ending trilogy of "Utopia," "The Sound Of Drums," and "Last Of The Time Lords" ... which ended up utilizing none of my ideas. Oddly enough, it ended up contradicting quite a few of them!)