If I have a big Project I am collaborating witho thers in, I sumetimes use Spreadsheets to organize the subprojects and next actions in a GTD-like manner (without them knowing... ). In these cases I sometimes just have a placeholder in my system under the general project entry, but the subprojects and next actions are not in my system. Of course I have to use this rarely and be careful about not branching out of my system too much.
I experimented with using a spreadsheet for actions, with the project as a column of the action. I stopped using it for some reason, but it wasn't so bad as to not be worth trying. I think there's a post here, somewhere, with how I set it up.