h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Baby Monitors are completely arboreal until they are large enough not to be eaten as snack food by adult monitor lizards.

I have a baby monitor on my lap top....its cute

Aren't Baby Monitors the people who check you have a Baby Pass when you're out in the Baby during lesson time?

They can be, yes they definitely can.

Baby Monitors work by transmitting radio waves from the babies microphone to the parent's receiver. These are very useful devices except when used near military installations.
The radio signal, whose frequency is 49.200MHz NFM, can also be picked up quite easily by hand held radio scanners available from electrical retail outlets. This can be rather annoying to radio enthusiasts during the early evening as the constant humming frequency overrides weaker aircraft and shipping signals.
The tables are turned however, when the parents retire to bed, as most of them only switch off the 'hissing' receiver downstairs and forget about the silent transmitter plugged in in their bedroom. As anyone with a scanner will tell you, it can save a small fortune in premium rate sex lines.

We discovered another use for our baby monitor. The receiver is great at finding where your house electrical wires are routed and therefore can prevent you drilling holes in them and having a nasty accident.

Are Baby monitors anything like Milk monitors?

Er..............no.