TreeNotes

From Alexander Buzaev:

TreeNotes - is a versatile information manager that is flexible enough to accommodate any kind of data:

Sometimes the information you want to store isn't in a set format. That's when you need a free-form PIM program that's flexible enough to accommodate any kind of data. If your personal information fits into a traditional PIM program like a square peg in a round hole--and the data lends itself to being structured hierarchically--then you should definitely check out TreeNotes.

The program has the look and feel of Windows Explorer. A plus sign beside a data node indicates that additional information is available on lower levels. Double-clicking on a node expands or contracts the node's tree to include or exclude the next level of nodes.