DMM's Pivot is a fantastic device from the Welsh Wizards with a premium lightweight karabiner.
A brilliant update of the classic Guide Mode Belay device (belay devices that allow you to raise a pair of seconds safely and securely without constantly holding the rope).
The Pivot has a special designed ... Pivot ... instead of a fixed loop as is the norm, what this means is that when bringing up a second who then requires lowering it is easy to clip a spare 'biner into the smaller loop and tilt the device back allowing the rope to run through easily. Via in shop testing it seems to be work superbly and I've got one to play with in the real world to see how it performs there.
On single pitch Trad routes with nice and easy tree belays like Shorn Cliff I can perhaps see it becoming common to lower seconds rather than them faffing around taking them on and off belay to abseil.