Vampire power a.k.a Standby Power
"Vampire power" is a term generally used to refer to those small loads that suck power all night (and generally through the day too) without much benefit to us.

There is an excellent example of tackling this in McKay's excellent, and freely available online, book Sustainable Energy Without the Hot Air. See Chapter 22 Efficient Energy Use.



Figure 22.2. Efficiency in the offing. I measured the electricity savings from switching off vampires during a week when I was away at work most of each day, so both days and nights were almost devoid of useful activity, except for the fridge. The brief little blips of consumption are caused by the microwave, toaster, washing machine, or vacuum cleaner. On the Tuesday I switched off most of my vampires: two stereos, a DVD player, a cable modem, a wireless router, and an answering machine. The red line shows the trend of “nobody-at-home” consumption before, and the green line shows the “nobody-at-home” consumption after this change. Consumption fell by 45 W, or 1.1 kWh per day.


  Does it do any good?


You can assume from the word 'vampire' that the term is derogatory. This is because the energy is (generally) wasted and little or no benefit is obtained.