I rarely talk about apps these days having switched careers and not having projects to manage anymore.

But I currently have the project of secretly arranging my wife's 60th birthday celebrations in August. It doesn't sound like much but it involves two separate events in two separate locations on different days with differing sets of guests.

Enter good old Workflowy to the rescue! For me I find it simple and powerful with just the right amount of smarts. Basically a bullet point/ lists app BUT each bullet point is its own separate node/ page/ bullet point that is in turn infinitely zoomable enabling as much or as little complexity as you want. It's such a fiendishly simple yet powerful app that I can't really articulate its usefulness so, just go and check it out...