Open Source and free software available on Linux.
This software sends network information (IP address, list of nearby WiFi access points, screen capture, photos from webcam ... all encrypted with GnuPG).
Description and download.
Intel Anti-Theft PC Protection
Some computers are equipped with this technology as mentioned at the beginning of the trick, making it possible to disable the PC remotely.
Some software allows you to remotely take control of one or more computer(s), and therefore may also be used to see what is being done with your computer in case of theft, retrieve the IP address being used ......etc