Trello – work collaboratively with others to plan events. Easy to learn and it’s free. Set up cards such as To Do, Doing, Done.
Xmind for mindmapping – to capture and organize my own thinking on a laptop or iPad.
Ginormous Stickies – This one is high-tech low tech. It is a paper pad that has its own table-top easel with an adhesive strip on the back. Think of it as a big Post-It Note. Easy to use, easy to move around and stick on a wall. These are not free but ever so useful.