Zim - a desktop wiki and outliner

I like and use Tomboy, but for some things Zim (hierarchical, grouping, etc) seems a better fit. From the website "Zim is a WYSIWYG text editor written in Gtk2-Perl which aims to bring the concept of a wiki to your desktop." I'm using it at work, and I installed it on my son's desktop for school related note taking.