Slashdot
I made these with RRD Tool using a piece of software called DigiTemp. It is a pretty standard Linux package that allows you to read a 1-Wire LAN using a serial port. I first had to make a serial adapter which consisted of about 4 diodes and a few resistors. I soldered these directly into the back of a 9 pin serial plug and covered them with the back-shell. I terminated this cable with an RJ45.
My 1-Wire LAN is run partially over flat phone cable and partially over CAT-5. I have two on CAT-5 running about 30 and 50 meters and two on flat phone cable, one about 150mm and the other about 10m.
Digitemp maintains the RRD (Round-Robin Data) files and I periodically generate the graphs on these files. They are updated every 5 minutes for internal viewing but are updated externally (What you see now) every hour.
The sensors I have are DS18B20. They are small. The ones that I have are the TO-92 packaged versions.
I will include some more data, circuit diagrams etc later; probably in the wiki.