Sure,
the URL to the lookup table is actually in the source code in the sketch, just by the lookup table itself. 
It's from the data sheet for the EFS-10 humidity sensor. Here: http://www.produktinfo.conrad.com/datenblaetter/150000-174999/156545-da-01-en-Feuchtesensor_EFS10.pdf
I got the sensor as a present and really don't know so much about it other than it being sold by Conrad.de. It is the first time I use it and I can't say it was very easy. I am not used to generating AC signals to drive a sensor and then having to work out the impendance of it from the (volt) value you get from analogRead() didn't make it easier. Now add 2d-interpolation to that and everything gets a little too complex for a beginner like myself.
The LM335 is a common and easy-to-use temperaure sensor in a three-pin transistor like package. Didn't give me any trouble at all and pretty much worked the first time I hooked it up.
I am trying to incorporate your suggestions now BTW. Will report back once I have it working, hopefully tonight.
Anders