Is it supposed to be all-analog or micro-based?
You can use a current monitor to measure the current (even a diff amplifier sensing the voltage across a series resistor will work). Here are some examples **broken link removed** Linear Technology also make some good ones, as do Texas Instruments.
The voltage is measured simply right after the current monitor. To multiply the values you can use a micro or an anlog multiplier, but scaling the output will be more difficult.