I've built my own humidor monitor, using an arduino microcontroller board, a cheap resistive humidity sensor and a LM35 temp monitor:
Controller image
I've only had it running for a short time, but here is a graph of about a weeks worth of data for anyone interested. It is just a simple desktop humidor, sitting on the desk behind me in my study.
The data (might take a while for the graph to load, be patient):
https://spreadsheets.google.com/spreadsheet...uthkey=CJybpb8P
This controller is going to have a relay added and control a wine cooler + active humidifier at some point in future, this is just the first step so I can learn how to do everything needed It should also be noted that I am not 100% certain my method of working with the humidity sensor is ideal, so don't read too much into the data.
If anyone wants to know more about this, I don't want to derail this thread so please post here. I just wanted to contribute some data.