The Idiot's Lantern: Magpie Electricals was the name of the shop owned by Mr. Magpie up until his death in 1953. At some point Mr. Magpie was contacted by the alien entity which called itself the Wire and was instructed to sell television sets cheaply ahead of the coronation of Queen Elizabeth II. It was all part of the Wire's plan to reconstitute its corporeal body. Mr. Magpie was killed by the Wire but somehow his business survived long into the future.
The Runaway Bride: When the Tenth Doctor flicked through various websites on a mobile phone, Magpie Electricals briefly makes an appearance.
The Sound of Drums: Martha Jones' television was made by Magpie Electricals.
Voyage of the Damned: The space cruise-liner the Titanic had a Magpie Electricals microphone. Wilfred Mott also had a Magpie Electricals television on his newspaper stand.
The Mark of the Berserker: Sarah Jane Smith's PC was made by Magpie Electricals.
The Eleventh Hour: Various aspects of the Eleventh Doctor's first console room were branded Magpie Electricals including the monitor, the typewriter and the keyboard.
The Beast Below: Magpie Electricals still seemed to exist in a similar form to it's original aboard Starship UK as there is a Magpie Electricals store on the ship.
Day of the Moon: River Song's scanner was made by Magpie Technology. She used the scanner a number of times during her adventures with the Doctor.
The Magician's Apprentice: The Twelfth Doctor owned a Magpie Electricals guitar amp which he used in Essex in 1138 on a tank. He kept the amp in the TARDIS and continued to use it (like in Before the Flood).
I am fairly sure that's the lot but there may well be some I missed. The Doctor Who team have a few of these ongoing jokes and I guess it's also a handy way to cover up brand names on electrical items!