I used a WiFi smart switch and a USB thermometer to make a sous vide cooker. I plugged a slow cooker into the smart socket, put the thermometer in it, and wrote a program to turn the switch on/off depending on the temperature the thermometer registered.
A friend of mine brute-forced the access key on a particular piece of industrial hardware by using an X10 outlet relay module, predecessor to today's wifi-connected smart sockets. The key was only 4 digits long and it would lock out after 3 attempts and require a reboot, so he was looking at a few thousand reboots each taking a minute or so. Easy enough to run over a weekend.
It ended up wearing out one relay, but he had a spare and just swapped it in and restarted the script from where it hung up. For the cost of like $30 and a few days, it gave us a new unobtanium unlocked unit.
