Handy little
gadget:

http://www.amazon.co.uk/VicTsing-Dis...ty-Smartphone/
dp/B00M7TA2D2

http://tinyurl.com/lb779o7

Other similar devices are available for less but they use 7 segment
LED displays. With the limited power availabilty on USB you don't
want your meter soaking up those precious mA's.

Seems to work pretty well but not had a chance to play properly (it
only arrived this morning). Shows the voltage droops on a 2A USB
supply when powering a 2TB USB HHD which is drawing 240 mA all the
time but spikes to at least 680 mA on spin up. The measuring interval
is too slow to really show such spikes though. It also has a mAHr
measurement, that drive has consumed 2,274 mAHrs in about 9 hours,
ties in but it's only maths...

--
Cheers
Dave.