If I was to try and figure out the greatest source of ... call it "enjoyable gaming time" or "lost productivity hours", whichever you please .... it would all fall on the shoulders of E. Gary Gygax, the "founding father" as it were of Dungeons and Dragons. Gary's creation would inspire many a teenage kid (and even a middle-aged computer geek) to spend many an evening huddled around a card table with strange-shaped dice, speaking in stupid accents, scribbling cryptic notes on scraps of paper and, for a few hours at a time, pretending to be somebody completely different.
Gary's health had been bad the past few years, and I felt really lucky when George and I met him last summer at GenCon - the gaming convention he had founded 40 years prior. He was as personable as any man could possibly be, warm and friendly, and very understanding as both George and I stood there with copies of all our first-edition books trying to get him to autograph them all (which, to his credit, he very patiently did).
Rest in peace, Gary, in whichever plane of the multiverse you'll call home from now on....

When it's all said and done, I can confidently blame his games for ruining my college career (well, not ruining, more like ensuring that I wouldn't have pursued a career I wasn't cut out for) on this man's shoulders. And I loved every minute of it....
True story, my first exposure to D&D was from my grandmother at a 1980 New Years Eve party. She tried to get my family to play D&D which was "the new fun game" at the time and they horribly failed at it. Unfortunately that first edition box got tossed out at some point in the mid 1980's....
Gary, thanks for confusing a bunch of 50 & 20 somethings back in the early 1980's :-)
I only played a few times, but respect enough die hard players to respect the game.
My new Favorite Comic Strip had a great 3 panels on the topic:
http://xkcd.com/393/