shell:folder Shortcuts

From Start/Run or from Windows Explorer address bar in WinXP:
shell:sendto
shell:desktop

Some registry locations of shell folders:

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders

References
Note: I could not find this documented on any Microsoft web site.