Mac OS X application developer The Omni Group has released OmniOutliner 2.1, an updated version of their outlining and organizational software.
OmniOutliner is a Cocoa-native application that enables you to track multiple to-do lists, with optional checkboxes so you can track your progress.
OmniOutliner 2.1 adds new toolbar items, Notes exporting and printing, improvements to printing, and increased AppleScript support.
OmniOutliner is available both in a limited free version and a licensed version that costs US$30.