For example:

Coronation Street - Betty's Hotpot
-The Cobbles

Eastenders - The Queen Vic Bust


Anymore?

"Benny" hats. - Crossroads

Hilda's "Muriel" and flying ducks.

Eastenders - Lauren's sandwiches

Pat's Earrings - EastEnders

Derek.cap
shirley boots

Omg.how could i.forget those everything about pat was a legend

Ena Sharples' hairnet

oh yes! and the serving hatch!

Kevin's purple jacket

...and if we have Ena's hairnet then what about Hilda's hair rollers and headscarf?

Deirdre's chain hoopy belt!

Massod hammer
and the argee bargee mad guy wooden spoon

Hayley's red anorack.

Zak's hat and Marlon's pirate's helmet.

Debbie Dingle's year's supply per day of mascara

Edna's hat

Kevin Webster's moustache.

Roys 'manbag'.

Bianca's horrible jacket (which didn't she sell then suddenly have it back on the next day?).

Max's champagne.

That Frank Butcher picture Janine has.

Tracey's voice box.

Any and all children in soaps -- they're like urban legends. Spoken of, but never seen.

ETA: Also the magical childminder and/or nursery that swallows up these mythical children for months at a time and somehow brainwashes the parents into forgetting about them.

PMSL!!

Fat Brenda... the myth of her

Except, sadly, for the 40 year old going on 8, Barlow brat Simon the Tram-dodger.

Also the Dark Lord Cora has stashed under her turban-like hair.

Ah yes, the mystery Streetcars receptionist