CAMERA
Of course the last thing on your mind during an apocalypse is getting a spiffy new profile picture for Facebook, but a camera is useful for so much more than capturing memories to treasure for ever.
Cameras are more readily available than binoculars or telescopes, and the zoom function will aid you on your reconnaissance missions. Also, as most cameras now allow you to view pictures on a tiny screen at the back, you can spend more time analysing a situation from the safety of your base without having to rely on memory or having to find a printer. If you are on a scavenging mission and running back to your safe house, you can also hold your camera aloft and take random pictures of streets and shops as you run. Later on, you can look through the saved pictures at your leisure and identify the areas that may be worth going back to. You can also use the camera to take pictures of the more attractive members of your team during strip searches for bites. As porn will be in short supply these will come in handy on cold winter nights.