Outlining is a great way to organise ideas, but they can get cluttered up fast. Oak Outliner is a webapp that supports local storage and makes organising outlines dead simple.
Oak Outliner comes from the developers of the plain text writing app Folding Text and it works in a similar way. You can create outlines in plain text, and then instantly collapse sections to make everything easier to read at a glance. It works surprisingly well, but once you start digging a little deeper into the options you'll find that Oak Outliner is a bit more powerful then it seems. It comes with its share of keyboard shortcuts, you can use tags to instantly find what you need, and you can organise your entire outline without ever touching a mouse. Your file is saved locally on your computer, and you can export it in plain text at any time. Whether you're outlining a massive project or you just need a way to keep track of of a few to-dos in your browser, Oak Outliner is worth a look.