I suppose its time to make a parts list in case anyone would like to replicate the controller (easily). I'll work on that soon and post it up.
I just got my break out board that'll allow me to datalog with the RBBB (really bare bones board) arduino since it has no onboard USB converter. The code is already there, its just commented out, so no real changes will be needed except setting up a delay so it only datalogs every 5 minutes or so.
I'm also thinking an LCD display would be really nice, add a few buttons and you can cycle through data, manually set the differential temperature, even turn the unit on and off all from a 'control panel'. Unfortunately, I've never used an LCD before. But, it'll be another learning experience.