So after reading this post, I got the idea to make a system that can measure EU flowing through a cable (mostly for SMP, to charge people for energy, but I'm sure are other uses).
It works by alternately charging and discharging a batbox/MFE/MFS. The picture shows it in the discharging phase - left is input and right is output (with an extra batbox for buffering). Because the batbox is charging half the time, the maximum average output is 16 eu/t (or 64 with MFE, or 256 with MFS).
At the bottom left is an output wire - I have it connected to a pulse former then a redstone engine, which moves a piece of dirt from one chest to another with every 40000 EU. That way, I could come back every now and then to see how much energy the customer has used and charge them for it.
Unfortunately, I don't see much use for this in the server I play on, because of its size (we have 10x10 town plots, and the town is the only place an electric company would be useful. Although as I was writing this I remembered RP2 devices can be vertical - the meters could possibly be built vertically under the 3-wide roads...
Edit: Forgot to mention - it needs a certain minimum amount of current flow or it will overcharge (further edit: overcharge as in charge too much money, not as in overcharge the batbox). If you feed, say, a single luminator from the output, current will stop flowing when it charges, making the circuit think the batbox is empty. There's no way around this as far as I can tell. A similar thing happens with the input. It will think the entire 40,000 EU has been transferred when really only one packet has.