This article (including video) credits a signal mirror for the rescue of New Zealand woman Kushila Stein adrift in the Aegean sea north of Crete this Sunday:

"Fortunately, by using a mirror to reflect light, Kushila was spotted by the Greek Coastguard and was saved after two nights adrift."

Other articles cite the signal mirror was used, but not what the rescuers actually spotted:

•The New Zealand Herald said: "She also pointed the small mirror she kept in her backpack at the sun to try and attract the attention of any planes that flew over." and "She had been located 55 nautical miles off the north of Crete about midday on Sunday."
•The BBC said: "Ms Stein put a red bag on her head and used a mirror to attract attention, reports say."
•Yet another report said: "Whenever a plane flew overhead, she pointed a mirror toward the sun, hoping to create a flash that would attract passengers' attention. "

• The Daily Mail Australia article didn't even mention the mirror.

I always make sure I have a mirror or two along! Good links.

I overlooked this rescue from May 22, 2018.

His hiking companion injured himself in the Grand Canyon,
and he used his PLB to summon help, but the helicopter
was having trouble spotting them. Per the PLB owner:

"The search and rescue team had a hard time spotting us from the air. I used a signal mirror and the pilot said that’s how they were able to locate us."

So - even if you have a PLB (and you should) the signal mirror is still a good idea!

Story here: https://www.acrartex.com/stories/tapeats-creek-arizona-usa

Regarding the 7/15/2015 rescue of Tim Gorske:
Tim Gorske's PLB was an ACR ResQLink, not a SPOT.
He tells his story here:
https://www.acrartex.com/stories/803eae6e-706b-4b79-8cb4-8c52574f3cec

I have a mini 1.5 x 1.5 mirror in my kit.

[June 28, 2020, Scotland] 77 year-old George McGowan saved himself after a motorbike crash by flashing a police helicopter with reflected sunlight off the broken mirror from his bike. He spent 24 hours outdoors.

Safe, OAP biker who was lost for 24 hours... then found in a flash

Quotes from the Scottish Daily Mail:

"But luckily, quick-thinking George McGowan had seen the police helicopter as it searched for him, and snatched the broken wing mirror from his motor­bike to catch the sun and signal the pilot.

"The helicopter pilot {said} had he not done that they wouldn’t have seen him."

"Karen McGowan, a member of Mr McGowan’s family, thanked those who had taken part in the rescue, and said he was recovering in hospital."

{ if the link above is dead, use this Archived Link )

An impromptu signal mirror is better than no mirror! It got the job done.

I almost always carry one. Not used that often, but very effective when needed.

[I seem to have overlooked this one at the time ]

Air Canada Flight Diverts to Find Missing Yacht

Passengers aboard an Air Canada 777 diverted to look for a distressed yacht near Sydney, Australia, checked out a GPS location from an emergency beacon at 4,000 ft altitude.

"The crew and several passengers spotted the yachtsman’s signal mirror"

That's a cool story.

Do wonder how much bureaucracy and red tape had to be dealt with to get a passenger plane involved.