There appears to be a resurrection on the OS X platform in the category of outlining apps. Two super outlining apps from the 1980s, which still run under Classic, are freeware: Acta and MORE. I've used Acta since the mid 1980s.

Acta
http://www.a-sharp.com/acta/

MORE has a few quirks under Classic, but it offers a spellchecker, bullet and tree/organization chart creation from outlines, slideshow creation, and also pioneered 'cloning' of outline items -- essentially outline item aliases that dynamically change the content of all clones when you change one. I've dabbled with it, and see why it still has many adherents:

MORE
http://www.outliners.com/more31

For many years, Microsoft has included basic outlining in Word, most recently available through an Outlining toolbar is the OS X version. It does a serviceable, basic job:

http://www.microsoft.com/mac/wordx/wordx_main.asp?embfpath=howtox&embfname=wd_writeresearch.asp

Inspiration, which has been out for several years, is now marketed primarily to educational institutions as a tool for students:

http://www.inspiration.com

Userland's web-app Frontier, which was written by MORE's original programmer, Dave Winer, has built-in outlining capabilities, but at $899 is not aimed at people interested in basic outlining.

Userland Frontier
http://frontier.userland.com/

There are now a host of new, OS X-only outlining apps as well.

Outliner 4X
http://outliner4x.macosguru.de/

Liner
http://www.imediasw.com/?p=products&s=liner

OmniOutliner
http://www.omnigroup.com/applications/omnioutliner/

NoteTaker (duplicating the look/feel of the old 'Notebook' NeXT app)
http://www.aquaminds.com/index.jsp

Idea Knot ("Brainstorming tool")
http://www.stayatplay.com/ideaknot/

IdeaSpiral
http://www.midnite-liteman.com/ideaSpiral/index.shtml


Has anyone used any of these new apps under OSX? Can anyone compare them?