Stopwatch - I bought a basic one when I did my IMC, together with a yoke clip and a gripper to hold the IFR plate. Never fly without it. Excellent value at £20 the lot.
Clock - I think it's a C of A requirement that all aircraft must have a clock, and that it doesn't work. Ours is clockwork, I think electrically wound - but the electricity to wind it comes from the "cold" side of the master switch so the clock runs down after two days unless the aircraft is flown. It has a winder on the front, which gives that warm feeling of contributing something when I wind it up. It then ticks erratically while we're airborne.
Age and humidity/vibration have taken their toll, and it no longer ticks while on the ground, whatever is done to it. I did ask if I could fit one of those simple, reliable battery and quartz clocks like the missus has in the kitchen. Answer was NO - they're not certified airworthy. It's more important that the clock is airworthy than that it works.
I wear a watch. I have a Breitling whose stopwatch doesn't work (long, sore point) but the stopwatch above does sterling service.