I thought this topic might spur some interesting opinions. Over many years, as a woodworker, I have seen many useful and not so useful improvements added to the tools we use. An incomplete list of these (not exhaustive by any means) could include:
1) plastic housings (improved grounding protection)
2) battery operated tools
3) soft start & variable speed control tools
4) keyless chucks
5) laser projected lines on miter saws
6) various pneumatic nailers & staplers
7) various jointing devices (Festool -loose tenon, Kreg-pocket hole jig, Lamello-bisquit etc)
This list could probably go on for a few pages.
These improvements come out from the tool manufacturers and you wonder which one is worth investing in, versus a perfectly good one you currently own.
There is also a number of hand tools which seem to be handed down from father to son, or a mentor to student which will never be obsoleted. Examples might be, a Stanley 130 (push-pull screw driver) and any number of fine planes and chisels. Anyway, I post this topic to see what you fellow WW's feel. Joe G