Pocket Freemind is an open-source Windows Mobile application for taking notes in a hierarchical structure. This allows you organize your notes as you take them. The file format used by Pocket Freemind is compatible with the desktop application Freemind, an open-source mind-mapping application. Although Pocket Freemind uses the same file format as Freemind, Pocket Freemind is not techincally a mind-mapping application because it does not display the data radially. However, you can still use Pocket Freemind for this purpose, as it was designed to be a way to create and modify Freemind mindmaps on the go.
Pocket Freemind requires the .NET Compact Framework 2.0 to be installed on your Windows Mobile device.
To download, visit http://eringal.com/pocketfreemind/