Started in the newsgroup rec.games.video.classic back in 2000, Feb 6 of each year has been recognized as Atari 2600 day. Based on product codes, cx-2600 was Atari VCS day in 2000, and cx-2601 made Feb 6, 2001 into Atari Combat day.

To that end, this year's holiday is cx-2611, so Happy Atari Indy 500 day to all this year.

And for the record, in Europe where they do it as day-month-year, yesterday (as of this post) was PAL 5200 Dig Dug Day (cx-5211). (Yes, I know, there was never a PAL 5200 commercially produced, but for the sake of date structure, we used to acknowledge it.)