I bought a
Kill a Watt meter last year. It is a useful tool to determine what is not truly off when it is off. In general, you electronics will have a transformer inside them and at at minimum they draw a small current when no current flows in the secondary circuit.
Using the meter you can quickly determine what has load when off and how much. How much is important in that if you want to automate the switch off, you need to make sure it is worth your money for the equipment to do so. Items like
this smart switching power strip or
this one, will detect current is low enough to be considered off and thus switch off the anciliary equipment in the designated outlets. E.g. if you turn off your computer then the screen, printer, scanner can all be switched off also. The beauty of the system is that you don't have to remember to hit the power strip switch every time.
You need to know you electricity rate - a rarity among many unfortunately - to determine if the power strip is cost effective. Simply multiple the hours in a year an item is NOT in use by your rate per kWh and you know the cost of leaving it on per year. See how this compares to the cost of a power strip and decide from there. My rates are obscene and even then, it take about a 15 Watt load on for 8 hours a day to break even aftet one year. The Kill A watt will measure the Watts, kWh, current for you.
I discovered my communication gear - modem, phone, laptops etc - were drawing considerable load when they were OFF and even ON. So I got a simple timer, and connected it to the circuit. I set it up to switch off late at night and switch on in the morning. That 8 hours a day when I wouldn't be using the gear anyway, would save me a few dollars a month on electricity bill. Pay for the timer in about 3 months.
I say this to say there are many ways to do it: auto switching, timers or manual. But measure what you actual have and determine cost effectiveness of the solution (including the hassle of your time). Otherwise you are guessing and could be very wrong. I think most people tend to OVERestimate the draw on offline items. It will not make a dramatic difference to your bill in many cases.
As an aside, for those of you really into efficiency, this is another benefit to the kwH meter. (I wish they made a 220v version for the likes of water heaters). You can make your improvements (heater blanket, sealing fridges, heater timer etc.) and measure the before and after rate of use. The power draw will be the same but if it comes on less often then the kWh (hence your bill) will drop.