Handspring Treo 600 (2003)

 The quest for the perfect palmtop/phone hybrid hit a new milestone with the Treo 600, released by upstart Palm competitor Handspring (the company founded by Palm founders Jeff Hawkins and Donna Dubinsky) before that company was itself swallowed by Palm. Slim enough to fit in a pocket, yet wide enough to hold a BlackBerry-esque QWERTY keyboard, the Treo quickly became the It gadget of 2003-2004, eclipsed only by its own successor, the Treo 650.