OmniOutliner Essentials (was OmniOutliner) is a flexible program for creating, collecting, and organizing information. Give your creativity a kick start by using an application that's actually designed to help you think. It's like having an extra brain - one that doesn't keep losing the car keys.
You can use OmniOutliner's document structure to create hierarchies of main headings and subpoints that can be expanded and collapsed, which are immensely useful when it comes to brainstorming new ideas, drilling out specifics, and lining up steps needed to get everything done. But you aren't limited to outlines - you've got multiple columns, smart checkboxes, customizable popup lists, and an Über-innovative styles system at your disposal.
Use OmniOutliner to draft to-do lists, create agendas, manage tasks, track expenses, take notes, plan events, write screenplays...and just about anything else you can think of.