Welcome to another installment of Gadget Dreams and Nightmares, a weekly look at the treats and horrors revealed as manufacturers pull back their curtains. Behind door number one is a selection of updated activity trackers from one of the oldest dogs in the yard, with the other shiny prizes including a music controller, a smart accessory for police firearms, and the planet's thinnest smartphone. Nary a week goes by without some upstart announcing a new or updated fitness tracker. This time, however, it's one of the pioneers in the field.