I'm aware of the FolderBrowseDialog and FolderBrowseDialogEx. However in my opinion these are both inferior to the below type of dialog:
This is more in line with the open file dialog, and gives access to the navigation pane (or whatever it is on the left).
I've seen it in a few programs (shown below is TortoiseHG), which makes me suspect that it a semi off-the-shelf component, and I'm just curious whether one is freely available. Unfortunately google-fu fails me and all I can find is the FolderBrowseDialog/Ex - so my question is, is there a pre-rolled version of this dialog box (if not in the .NET framework then elsewhere) that I can use?