Okay, so this isn't, strictly speaking, an outliner, but it's a neat information manager with outliner-like characteristics!

I've just discovered Kanban Kit (unfortunately Mac-only, I fear), which is a very nice, efficient implementation of the Kanban task/project management concept.

What makes it slightly unusual are a couple of extra features: subtasks, and due dates. Otherwise it follows the standard Kanban column-based arrangement, proceeding left to right from 'Todo' to 'Next' to 'In Progress' to 'Done'.

You can divide up tasks or projects using tags – gratifyingly, you can attach as many tags as you like to a single 'card'.

While Ulysses is still my go-to task manager, I was looking for something I could quickly slap stuff down on in a very visual way. Kanban Kit fits the bill!

More info at http://screenisland.com/kanban-kit/