ElectroDroid is a simple and powerful collection of electronics tools and reference. It includes:
– resistor color code
– ohm’s law
– voltage divider
– resistor ratio
– resistor value/series/parallel
– operational amplifier
– LED resistor calculator
– various port pinout
– support EIA resistor series
…and more to come!

See more at What’s it page

The app is currently localized in english and italian, I’m looking for someone that want to help me to translate the program in others languages… please contact me!