Bajdi:
I also have the version with 4 encoders/motors, but don't really have a clue what to do with the encoders :~
Very cute!
I'm not using the encoders right now, but what you could do with them is find how far it has gone. For example, you put out "full power" but you don't know whether, after 3 seconds, you have gone one foot or five. Reading the encoder data back would tell you how much the wheels have moved. Off course that doesn't take into account the wheels slipping.