Meet Hub List, the productivity app that works the way you do.
Folders can have sub-folders and tasks can have sub-tasks! Tailor your workflow to follow GTD as little or as much as you like.
The downloadable Beta runs natively on Mac, Windows and Linux! A Web version of Hub List is currently being developed.
Switch to the focus view and eliminate distractions. Escape the big picture and get things done, one task at a time.