I just discovered that these commands exist while skimming the source code:
TargetPreviousEnemy
TargetPreviousFriendly
PreviousWeapon
PreviousMissile
EnableAllDevices
DisableAllDevices

The first two seem particularly useful when cycling through a long list of targets.

The code also shows the following, which I haven't found the correct XML for:
keyEnableAllDevicesToggle
keyEnableDeviceToggle00 to 31

Edit: Ok, I found the XML names:
ToggleEnableAllDevices (This disables all devices if they're all enabled; otherwise it enables them all.)
ToggleEnableDevice00 (This toggles the first device.)