I'm in with the Cordless stuff also. Still have 2 working Yankees [one with the wooden handle, the other with the red plastic handle].
Some other things would be the newer box hanging things, such as the ones that go between studs for upto 3 4s boxes to mount on. The other being the hanger / back end stops, which backs up against the drywall behind it - keeping the 4s box from doing the twist when someone plugs into a receptacle.
Before these arrived, we would cut sections of top channel [steel studs] for multi box support between studs, and layers of drywall, or small sections of CRC to keep boxes from twisting.
I'm so use to doing things "the old way", that I automatically figure that approach on jobs I B A LAMER
When the "Slave / Master" lighting was commonly used [a California thing], a few companies had some nice quick connectable Slave fixtures - those were labor saving.
Most fixture companies have those sliding pop-out deals on top of their 2x2 and 2x4 troffers. Those can sometimes be labor saving - but we normally get the lamps separate from the fixtures, so the diffuser has to be dropped anyway!
The slide in place deal (or "Noodle"
if Steve doesn't mind me borrowing the term) can be a major pain in the _______ [fill in your preferred word]. Pinching Ballast leads, loose fits, questionable ground connections, the list goes on...
Some of the "Labor Saving" stuff for switchgear, became more like "Labor Adding - In Future"!
Square D's "I-Line" stuff can be one of them. If not installed really tight, the plug-in contacts just fry out.
Same with the old Zinsco gear [can't recall the series].
I'll try to add some others later tonight, or tomorrow.