Mine is Perligo (https://perligo.io). It’s a digital writing critique group community I’m building simply because of my experience with software used in my Master’s program in creative writing. The program used discussion forums that were not designed for the types of collaboration and communication that happens in a writing group.
My goal is to launch this and have as many writers as possible use it. But if that fails, I know my old MFA cohort will use it with me, and I’m happy with that.