The present definition of the ampere is arbitrary, so it would be good to have a physically meaningful absolute measure for current. Ville Maisi at the Centre for Metrology and Accreditation in Espoo, Finland, and colleagues have managed to gang together 10 single electron transistors to make something like a 10-electron "turnstile", which can produce a precise current of 100 pA.
This is a a factor of 10 higher than previously possible. Scaling to higher currents, to a real current standard in terms of electron charge per second, appears to be within sight.