The Party Superstore was/is my absolute favourite London shop until it was bizarrely attacked and gutted during the summer London riots. They have been since adopted as a concession by the local Debenhams but you can still savour the full delights of the products and nonsense on line.
The most special and charming cinema (probably most deprived too) in London. A place to catch a classic or a new release. You can get a lifetime membership for £50, weekly £1 member screenings. A place where staff are as passionate about pictures as its visitors. A must visit for movie buffs.
There are many quirky book stores in London, but I really love the selection that Daunt Books have, they often have bespoke editions which you won't find in other book stores. Also, the people that work there are so helpful and knowledgable. I can never stop myself from walking in!