Original one, it is probably the kickstarter one too! I've got three running in my house. All run php either via http or on a loop/cron/schedule and interact with relay modules or 1wire temperature sensors. One monitors external temperature and sends the data to weather underground. One monitors office temperature and fetches data from my solar panels, then turns on the heating via a relay if I have excess solar energy. It also controls some outside garden lights on a schedule via a relay. One monitors two areas of the house AC to DC battery and inverter cabinet. All of the above also get ingested into a database for graphing. I also had a friend who wanted to remotely control their gate.. so they've got one using php and relay outputs. And finally.. for several years a school had a dodgy boiler which would trip out and only get noticed hours later (or if a weekend, didn't get noticed until too late on a Monday morning!).. an onion was eventually setup there using GPIO to detect the boilers failure relay output and send an email to the janitor/caretaker to warn them the moment it had failed. All would have been possible with a Pi or similar, but the form factor of the Onion and features + packages available made them ideal.