Here's a few I would want:
Force Logoff on the Start Menu // Forces user to have to log off when he presses 'Start' on the taskbar
Code:
User Key: [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\
Explorer]
System Key: [HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies\
Explorer]
Value Name: ForceStartMenuLogoff
Data Type: REG_DWORD (DWORD Value)
Value Data: (0 = default, *= force logoff button)
Disable the Ability to Right Click on the Desktop
Code:
User Key: [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\
Explorer]
System Key: [HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies\
Explorer]
Value Name: NoViewContextMenu
Data Type: REG_DWORD (DWORD Value)
Value Data: (0 = disabled, * = enabled)
Hide All Items on the Desktop // A real pain if used at school 
Code:
User Key: [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\
Explorer]
System Key: [HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies\
Explorer]
Value Name: NoDesktop
Data Type: REG_DWORD (DWORD Value)
Value Data: (0 = disable restriction, * = enabled restriction)
Disable Internet Access
Code:
Giving the link is easier: http://www.pctools.com/guides/registry/detail/*288/