> For instance, I use Trello as a scratchpad about various things I have going on. I've got about 11 or so person boards. Writing things down and applying a method to limit work in progress is really the corner stone of getting things done in my opinion.

I use trello extensively. I always have an "In Progress" list and an "On Bat" list. "On Bat" maxes at 5 items, "In Progress" always has two items per person on the board (and it should usually only be one item).