Trello is a great tool. So much so that it puts the screws to people like me (and others I've known) who have always complained about organization tools not being good enough. We finally have to face the fact that it's no longer the tooling--we're just too lazy to keep organized, or don't really prioritize it enough.
I think it's good also for the debugger documentation, though it has been on hold a bit. I'd really like to figure out a way to minimize the amount of C code used in its implementation, kind of like how I've wanted to push the REPL development into userspace. Now that the REPL is in userspace with some reasonable formulation, I think I could probably wire something up that looks like what I want for single-stepping etc.
There's also a parse project trello, which I made when the old parse wiki went down. I think it's a pretty good example of the usage, with a card for each parse construct:
It works well for these purposes, and I like using it. Has a good way of letting you organize the view of things.
As for gathering notecards about various efforts, I feel like there's no shortage of things to work on. It would be better if people stuck to one project they were personally passionate about and polished it, instead of collecting a million unfinished ones!