The DS1803 is a digital addressable potentiometer (this means that you can use up to 8 of those in one project) produced by Maxim-IC and it works on the i2c bus. I had often the necessity to trim my potentiometers without having phisical access to them so I think that using this type of potentiometer is a practical and elegant solution.
The DS1803 is double: the package contains two 256 steps potentiometers. It is produced in three flavours, DS1803-10, DS1803-50 e DS1803-100, with a trimmable resistance of 10k Ohm, 50k e 100k.
In the same family you can find the DS1844 wich contains 4 64 steps potentiometers, via i2c.
I wrote an Arduino Library for the DS1803, easily upgradable to the DS1844: you can download the library from my github repository DS1803 Library
Incluso nel pacchetto vi è il file di esempio che indica il funzionamento della libreria: è semplicissimo!