If you're the owner of a digital SLR, then the XSories Weye Feye may very well be something you're interested in. Its skill, is taking a live feed from your camera, and sending it, over Wi-Fi (hence the name) to your phone or tablet.
This means you can set up photos on a larger, more mobile screen and adjust most - if not all - of your camera's settings from as far away as the Wi-Fi signal will reach. This is handy if you're trying to snap nature, but it's scared of you, or if you just have a small studio set-up and want to move the models or objects around without having to pop back to the camera to check framing and trigger the shot.
It's also invaluable if you want to take a selfie, because you can easily focus the camera from a decent distance. You can also touch the area you want to focus on, which is a bonus because older SLRs without touchscreens lack this "touch to focus" ability. We found it was a bit slow to get a lock - about the same as using liveview, which isn't a massive surprise - but it's a good solution if you're on your own.
Professional studios have used this sort of thing for a long time, but this is £200 and allows you to do much of the same stuff, but on a more home friendly budget. One thing that we love, is that you can use it to trigger time-lapse shots. This sort of functionality isn't on all cameras, so the idea of being able to add it is rather cool.