I'm amused that's still going, one of my classmates qualified for and attended the Word championship hosted in Vegas many years ago.

As for programming prizes, "last week" if we're counting bug-bounties, "a few years ago" if we're counting CTFs, and 5 years ago if we're not.

Clearly there is an Excel community in the general sense but as far as I know it isn't centered around any particular venue - at least, not one at the scale of GitHub or Scratch