Cool stuff. It isn't often that Windows' Undocumented Features really are features and not bugs.

Windows + M minimises all windows (but leaves dialogue boxes open), whereas Windows + D really does clear the desktop.

Also, F3 on its own is search.
F2 on its own can be used to rename a selected file
F1 is Help (you knew that already though). F10 on its own is another key for alt (in case yours is borked).