Yesterday was celebrated as the the 40th anniversary of Dungeons & Dragons, according to the best evidence. Although we didn't play a tabletop game that day, my wife and I spent part of the day playing Diablo III on the Playstation 3. Our Level 51 characters are in the beginning of Act I in Hell Mode, our third run-through of the game together. It's a fitting way to celebrate this milestone. Any fantasy or sci-fi video or computer game where a player takes the role of a character, with levels and hit points and spells, owes its existence to D&D.
There were plenty of great posts and news articles leading up to and over the weekend about D&D's birthday, so I do not have much to add to that chorus. The most important anecdote I can offer is that, in addition to all the fun times playing D&D and the other role-playing games that followed it, rolling dice and telling stories of heroic adventure, the hobby is directly responsible for most of my best and lasting friendships.
For that and more, I have enormous gratitude for the pioneers of this weird and wonderful hobby of ours: Major David Wesely, Gary Gygax, Dave Arneson, James Ward, Dr. John Eric Holmes, Tom Moldvay, Frank Mentzer, and many, many others.