Note-taking in tree-like structures (reminds me a tiny bit of things like workflowy).

One neat thing is that it has the concept of 'global' and 'local' trees: you have one global tree on your machine (usually central place for any notes you want to add, that you can call up from wherever, a little like a wiki index or similar).

Then you can have many local trees that just live in cwd under .mind - perfect for e.g. keeping track of a project's todos (i.e. little code projects for example)