Products that I want #3: Network port blank-plugs

Many work in environments where there are network connections that shouldn't be plugged into certain bits of hardware. There are also situations where a bit of hardware should not ever be plugged into a network. Human behaviour and automation of tasks (habit) being what it is, if you plug a network cable into a bit of kit (e.g. a laptop) day in day out, then you pick up another bit of kit that is roughly the same, in the same location... then sooner or later accidents will happen and things will get plugged in where they should not be. Some solutions spring to mind:

• Colour coding network cables for different networks
• Designing the working environment to encourage certain things to happen and others not to happen, through either positive reinforcement of behaviours or placing active barriers (like the cable not reaching)
• Easy-fit different plug-socket interfaces. Add on a star, square, circle, whatever connector to the end of your network cable, uncover the fixing end (sticky bit or something) plug it in, and then snap the plug-socket interface so that you have one bit on the cable and one bit on the computer. The result is network ports intended for network X you have these little circular (or whatever) additions to the network port, which means you have to use the network cable with the circular interface to actually make a connection. This makes it hard to impossible to accidently plug in the cable to the wrong network, and also makes it harder for people to try and connect their kit to your network; they need the right shape interface. This could be taken a step further for those who want more security, the connections could more permanently fixed and be unique, making the physical connector like a key. Only those computers with the right physical key can have a physical connection to the network. Of course you could do things like cut the cable and remount a standard plug on the end and so forth, but any secure system needs a) defence in depth and b) defence that influences human behaviour and flags up inappropriate behaviour, which this offers.
• And.. network port blanks. I want a little shaped bit of plastic that I can pop into the network port that stops me from accidently plugging in a network cable. More 'seat of the pants' solutions include using sticky tape or tac, but these look tacky and don't last well and muck up the connection.