We have had incredible threads on note-taking concepts as a whole.
Here I would like to limit the discussion to the basic motif - a tree-style (often with tabs) note program.
Three come to mind.
Keynotes-NF (Free, Open Source)
TreeDBNotes (Free and Pro)
AllMyNotes Orgranizer (Free and Deluxe)
Keynotes-NF is the open source followup to Keynote, when I use TreeDBNotes I must admit the interface is rather a bit more pleasant (a real factor in note programs) and AllMyNotes Organizer looks like the new kid on the block, with a DC discount and perhaps the most active development ?
I'm sure there are probably 5-10 other similars worthy of consideration, lets not include them other than en passant notice .. unless they are overall really right there in the mix, with their own advantages.
Some of the issues to consider.
Search strength and speed and utility
Portability, integration with web in any shape, manner and form
Licensing on USB-Work-Office puter with 1 license at a time
Database facilities - some user defined fields
Note and a source URL logically connected (not just urls in a note) - e.g. consider this for a research database
(this is a pseudo-bookmark facility, if a note program could be linked with a linkman type of program, even better)
Support (forum, developer response)
Attachments and pictures
(Add 10 more here)
I would like to personally make my decision for the next couple of years, right now I am toggling back and forth from Keynote to TreeDBNotes and the BitsDuJour and DC discounts for AllMyNotes caught my notice, leading to the post