Quadra-Trac, a four-wheel-drive system developed by Jeep
Computing
The Qt (toolkit), primarily a cross platform graphical widget toolkit for the development of GUI computer programs
QuickTime, a multimedia technology from Apple Inc.
Music and television
QT, a Danish europop band
QT: QueerTelevision, an LGBT newsmagazine which aired on Canada's CityTV in the 1990s
Religion
QT, in Christianity; "Quiet Time", referring to a personal time of spiritual meditation and reflection, usually involving prayer and Bible study to make the intimacy with God and knowing God's will
Slang
"Cutie," a homophone derived from the pronunciation of "QT"
"Quiet," as in the expression "on the Q.T.", meaning "secretly" or "in confidence" (origin)