I made this projecto for the http://hackaday.com fubarino contest with a small easter egg in the end.
It uses a LTC2400 adc from coldtears electronics wich is about 19$ and has a nice arduino librarie
the display is from dx.com and it is based on a TM1838 here about 7$ and i thank tronixstuff for some usage explanation here excep that the leds colours are wrong with the librarie (red is green)
The code is here but it is very easy.
The project is not finished, and I must make more functions and solve some of the noise problems.
I will post more deveolpment in this blog
Thanks to de precission resistor voltage divider now I am reading up to 17V with 16777216 steps, so it is nearly a 1 uVolt resolution.