I do a lot of outlining in MS Word, and I sometimes play around with other outlining tools (Radio, SciTE). I sometimes wish for a tool that would let you structure a document as you work on it, in a flexible and freeform sort-of way, letting you switch from a hierarchic structure to a table (or back) and generally futz with the stuff you write to make it easy to navigate, organize and understand. Sometimes I contemplate writing something like that, or (better yet) finding it.
TreeLine is a small personal database program, built with Python and the Qt toolkit, that works nicely on Windows and Linux. It seems to fulfill all the infrastructure requirments for this hypothetical outliner-organizer I described above. It’s not what I’m looking for, though: too structured, forcing the user to think of the data model instead of letting him make it up as he goes along (and organizes and revised his thoughts). It’s nice, though, and would make a good basis for building what I want.