As far as instant/current information goes (extremely valuable when dialing in various techniques and mods), aside from the zemco unit, there was one case where someone sourced a flow meter and hooked it up to a bike computer (fuel consumed is measured as a "distance). Now you can do a lot better than a bike computer, i.e. arduino or mpguino for a starting point, but you get the idea.
http://ecomodder.com/forum/showthrea...html#post12516