If you want to measure how much energy you are using, can I recommend a simple webcalculator? It doesn't tell you which appliances are using the most energy, but it does give you immediate feedback on how you are doing, if you are trying to cut back, rather like weightwatchers for energy users. It's called Imeasure.org.uk
You take a weekly reading of your gas/electricity meters and enter the figures in. It tells you how much energy you have used and compares that with other households of a similar size.
(It's more accurate than looking at your bills, as some of those are estimated, so don't give you regular readings.)
There are other similar things out there, but we're finding this one quite good to use.
I'm not getting one of those, I don't need to spend money on a gizmo to tell me that I'm sitting here in socks and a blankie over my legs to keep warm instead of putting the heating on!
Less water in the kiddies bath, turn all applicances off, no lights on in rooms we are not in, having one day for oven cooking and then doing baking and everything while the oven is on.
What I need now is a whistling kettle - I used to have one that heated on the gas ring, it whistled and you HAD to get up and turn it off. Then dp got us an electric one and he keeps putting it on for a brew, not getting up when it boils, going back and switching it on again, not getting up for 10 mins again etc etc...
If you want to check your consumption you just look at the numbers on the gas and electric meters and monitor consumption that way. The more appliances you have on, the faster the meters go round. These gadgets are just a gimmick imo.