PC Outline. It's a DOS-based outliner. In 1986, my manager said "Here, you're organised. You'll like this" and he was right - I did. So much so that I bought my own copy. I still use it every day in a DOSBox DOS emulator on Windows 7 and Linux. I use it for passwords, todo and done lists, keeping track of work done for clients, functional decomposition, shopping lists and the steps for configuring and compiling the Linux kernel.
Personally, I haven't ever used PC Outline, so I don't know its features, but from many free outliners I tried I liked the Noteliner. Unfortunately I couldn't find a replacement on Linux (and I don't have time to learn Emacs + org-mode)
Also, there's not much learning to do for just emacs + org mode. By default there are context menus to help which also inform you what keyboard shortcuts are available. You might need to get used to some "odd" keyboard shortcuts, or turn on cua-mode to make it behave like you're used to, but otherwise, you don't need any advanced knowledge to get started.
