More than a dozen companies offer portable, digital outdoor camera systems known as trail- or game-cams, and most will work to monitor cabins, campsites and other rural sites. Most are battery powered with options for hooking into household current when and where available, and they retail at less than $200, with some basic models selling for less than half that. Several offer solar-power options for long-term use and most use no-flash, infrared technology to capture images or even video clips at night.