I would suggest looking at Geoff Chappell's page about explorer's command line switches. It lists all of the switches that Justin mentions along with the /idlist switch (though using this requires raw memory access, so it would probably be more interesting on SO than here on SU). The syntax for each switch is given, and some esoteric details regarding item specifiers are also explained.
- /separate - Launches this explorer instance as a separate process.
- /select [object] - selects the file or folder in the new explorer window
- Opens a new single-pane Window for the default selection. This is usually the root of the drive on which Windows is installed.
- /e Starts - Windows Explorer using its default view.
- /root - Opens a window view of the specified object.