Video baby monitors: little one way video and audio relay. So you hang this little video camera over the baby's crib, and you can hear and see what they're doing. It's the upgrade to what they used to have that was basically a one way open mic walkie-talkie. The one we use for our baby has infrared LED's and camera mode, so we can see him even in pitch black. Cheaper than a nice spotting scope, and easier to use (less eye fatigue at least). The Motorola one that uses an smart phone based app instead of a handheld screen has as long of range as you can imagine. The normal versions only go a few hundred yards with a clear line of sight.