Wow...nice, enthusiastic reactions!
I'm thinking of a challenge with a theme every 2 weeks (a theme that is well suited to work out in black & white) with annually a total of 20 themes, including 5 themes suggested by members.
In fact: in the summer there will be 1 theme per 4 weeks (instead of 2 weeks) and there will be no challenge by the end of the year, because everyone is too busy with other matters.
This B&W Challenge is going to be a fun thing, no competition, no prizes, but hopefully a lot of learning, experimenting and also experiencing how others approach a theme, everyone can participate - digital photographers and film photographers - with as many photos as desired during each B&W Challenge, as long as they are NOT color photos!
The starting point is, of course, that everyone intends to photograph intensively for every theme, with every challenge I'll state what the first, subsequent theme will be. So, ultimately, everyone can work on themes a few weeks in advance, if they wish!
(*edit* Because each edition also includes the following, new theme for the next challenge, extra time is created to work on themes, so, the possibility of eventually using images from your own archive for the B&W Challenge is removed)
Just start next week and see how it all continues, I think!