Things every hacker once knew... This is a fascinating essay by Eric S. Raymond. Almost everything in it is well known to me, though I don't think Eric would consider me a “hacker”. I'm five years older than he is, and I suspect I started with electronics (though not computers) a bit younger than he did – so some of the things he lists don't even seem that antique to me! :)
Update: first link fixed. Thanks to all who commented or emailed to let me know!