I'm in the process of adding various sensors around the house to improve the home automation stuff. I've tried adding a number of the 1-wire temperature sensors like the DS18B20 and have found that the 1-wire network isn't stable with the number of branches and length that I'm trying to run. (Not suprising I should note. The cable has been run as a star network which is near worst case).
So I'm waiting for PCBs to arrive to implement 8 separate 1-wire masters, which will allow much more in the way of sensors.
There's also a simple pressure sensors in here which is easy to do, and uses some sensors I had lying around. This is intended to measure the pressure differential across the air-conditioning fan. This will allow the HA unit to tell if it's closed down too many of the air conditioning zones and there's not enough airflow for the AC to function effectively. (At least, that's the theory).
A quick circuit to add 8 x 1-wire masters to the NGW100 AVR32 CPU board. See here for the software.
Pretty much straight from the data sheet for the DS2482-800.
This plugs into the NGW100 via the J1 connector and presents 8 x RJ45 connectors for 1-wire chains to be attached to. This presents on the I2C bus for the AP7000 CPU.
This is way overkill but I'll do a couple of these boards, and stock the parts box a little too. The I2C master board works out at being about $40 - $60 including PCB which is ok.