Something similar to FSL Launcher, where each tab is linked to a folder and auto refreshed when the folder contents change
This can actually be done with FSL Laucher with a little hack (see http://bit.ly/rDUg9g), but is not optimal. The paid version of ObjectDock also does it, but that is not free (and strangely disabling Aero on Win 7 messes it up visually).
The idea is to be able to drag and drop items across tabs, from the desktop to the tabs, or from the tabs to the desktop, and have the operations be reflected in the folder structure. Also, to maintain normal Windows' right context menu behavior on the icons.
Would also be nice: the ability to move icons about inside the tab, and for the locations to be preserved (kind of like the clustering of icons that can be done on the desktop).