Focus peaking... Having explored that on my Sony A77, its a brilliant thing for manual focusing. Only works on devices such as my Sony SLT or mirrorless cameras that have rather fine OLED viewfinders (don't just assume "no optical finder = rubbish"), but once explored, I'm no longer scared of using manual focus. Do other systems have this on the LCD screen?
For those who don't know, you get an effect rather akin to the display of burnt out highlights on the LCD display, but shows the areas actually in focus, rather than the blown highlights. This works both on the viewfinder and LCD screen, and even works on the LCD (it ain't got a viewfinder) of my RX100 compact, a pocket sized device i'm very pleased with.