A few things.

A National portable stereo thing (Tape decker, equalizer, detachable speakers) from the 80's

A Casio boxing calculator

A 80's spacies game, with box.

A 90's VCR

All stilling in working order.

This is definitely stretching the OP's topic but it uses electricity! We have got a kitchen "gadget" that is till running fine after 52 years! A Kenwood Mixer! 

I've got a Goldair alarm clock that dates back to the early 80s, still works fine.  Also have an Amiga 500 which is trucking along nicely, along with a 1084S monitor.  But if we're including computers then there are bound to be others with much older examples in working condition.  

Sony Clock radio - bought it at least 20 years ago. Still works fine (Snooze button doesn't work actually - but I never use Snooze).

About the same time I bought the clock radio, I bought a 'C' grade F&P ED56 sensor dryer - it's still going strong too. (B and C grade appliances were from F&P and usually were slightly used or had cabinet damage - I worked for a retailer that was an F&P dealer back then - bought a B grade fridge, C grade dryer and a real cheap intuitive washer when they first came out too).

When I was in the 6th form in 2002, we had just upgraded from dialup to "jetstart" (128k ADSL). My brother had a school laptop, so he unplugged the family desktop from the router whenever he needed to do "school work". I went out and bought an 8-port 10/100 switch to solve this issue. Cost around $100, which was a lot of money for a high school student. Anyway, it's been running 24/7 since then in my parents' house. I'm quite impressed that it is still going strong after 15 years! Especially since it was consumer level, not enterprise. I'm also glad I didn't cheap out and get a 10 Mbit hub, otherwise my parents would likely still be using it...

My Dad has a Bell and Howell 16mm projector that his Dad bought second hand in 1954. 

It still works, and has the most enormous transformer box I've ever seen.

The 1st "computer" I bought was a Casio PB-100. That was in 1986/7 I think. My father still uses it and it works. But does look worn nowadays. 

Ah, the PB-100. Back at uni in '94 a friend got his from Japan... What a beauty.

linw:

 

This is definitely stretching the OP's topic but it uses electricity! We have got a kitchen "gadget" that is till running fine after 52 years! A Kenwood Mixer! 

 

You must watch this, recommended with a cup of tea. 

https://www.youtube.com/watch?v=XnYPOkzy-oI (James May The Reassembler s02e02 Food Mixer)

I have a pong/tennis/squash TV games console from the early 80's/late 70's however before I can make a claim here I'll need to find my analogue tuning RF cable & check it is still going as I haven't tried it in a couple of years.

I am surprised by the number of clock-radio's in the this thread. These must from before the ship sailed on clock/radio quality. I have never found one that I would recommend to anybody else to buy. On all of my early ones the volume Pots wore out and went all crunchy & randomly loud/quite. Even tried buying name brands (Sony, Panasonic), but they went in the bin almost right away with unstable radio tuners and/or blindingly bright screens.

I have a JVC VCR that's about 18 years old.  Used it not so long ago with a PVR150 tuner to digitise a bunch of our old home video tapes.