Another good one is the 2010 Bushnell Trophy Cam.8MP,fast trigger,long battery life,compact and uses up to 16 GB SD cards.8 AA batteries and they make steel lock boxes to fit them.I picked up two,with steel lock boxes,for $200 each and free shipping.The steel boxes ordinarily go for $32-$35.I think dimensions are app. 3.5"X5.5"X 2".The same camera,with view screen,costs $50 more but also imprints moon phase and temp.
At any rate,you want a camera with a fast trigger speed,around 1 second,long battery life and the ability to set the delay time between pictures.You can decide if you need a view finder in the camera.