The last one to end on the spotlight is Dell which has recently announced to be working on a product to detect a person’s mood, for use in education, communications, cars and video games. Jai Menon, head of Dell research gave a few examples of benefits coming from such systems: “If I can sense the user is working hard on a task, an intuitive computer system might then reduce distractions, such as allowing incoming phone calls to go directly to voicemail and not letting the user be disturbed.”
Dell researchers have also used brain activity headsets by companies like Neurosky to identify users' moods. This worked on about 50% of cases, so accouracy is still quite low but the use of multiple sensors such as EEG, ECG, pulse oximeter to adjust values are currently being tested and hope to increase. Despite such limitations, Dell plans to release an off the shelf system in 2017.
Sources: http://neurogadget.com/2014/09/14/dell-plans-release-mood-reading-product-2017/10543, http://www.bbc.co.uk/news/technology-28642935