I got the game in beta 1.2_02 stage
when I first found redstone I didn't know what it was, so I used it for decoration
when I first made a jukebox, I kept rightclicking it (I had no records at the time) and eventually the game's normal music turned on, so I went a while thinking it did that instead
eventually though, my first minecraft map ended up getting corrupted, new chunks randomly appearing
one of the buildings in our world ended up being cut in half due to chunk errors
eventually the world just didn't start ever again, even when I tried to edit it using a world editing program it kept crashing, so I never got the world back again
my second world was fine though, yet that was lost when switching computers.