Dalekmania!

Conductor: "Room upstairs only!"
Daleks: "Doh!!!"

When I was young, I remember watching a TV showing of a 1967 movie starring the diminutive comic actor Charlie Drake. It was called "Mr. Ten Per Cent" and had a theatrical setting. At one point, Charlie walks into the auditorium, watched by the assembled cast on the stage. One character whispers to another: "So that's what the inside of a Dalek looks like...".
I cite this memory to illustrate how much Doctor Who - and the Daleks in particular - had become part and parcel of Britain's popular culture of the mid 1960's. Between their return to the programme in The Dalek Invasion of Earth, roughly through to the release of the movie based on that story, the Daleks could be seen and heard, or referenced, absolutely everywhere.
Programmes like Blue Peter featured them - the Valerie Singleton Dalek cake-making sequence appears as an extra on The Dalek Invasion of Earth DVD. They would pop up unexpectedly on variety and other light entertainment shows. Their biggest presence however, was in their merchandising. Anything that could have a Dalek added to it, would have.

• Books:

The first Dalek TV serial had been adapted as a novel by script editor David Whitaker in 1964 - renamed Doctor Who In An Exciting Adventure With The Daleks. Whitaker would also author The Dalek Book, and its follow-up, The Dalek Outer Space Book. These illustrated volumes gave a version of the creation of the Daleks, plus lots of useful information about the creatures and their world (they cannot see the colour red for instance). These books would have Terry Nation's name all over them, but it would be Whitaker who would write much of the content. Whitaker would also pen the stage play "The Curse of the Daleks", which ran at London's Wyndham Theatre between December 1965 and January 1966, offering an alternative to the traditional panto season..

• Comics:

Spinning off from the books, and also authored by Whitaker, were the glossy full colour Dalek comic strips in the TV Century 21 publication.

They began with Dal scientist Yarvelling's invention of the Daleks for the survival of his blue-skinned people, and would go on to feature the Mechonoids from The Chase. The gold spherical-domed Emperor was ruler of the Daleks. He would inspire the design of the Davros-Emperor in Remembrance of the Daleks.

• Toys:

Plastic Daleks hit toy shop shelves in every size and colour. For collectors today, some of these (frankly bizarre) colour variants are much sought after. There were tiny little Rollikins, which ran on a ball-bearing. Most popular, and commonplace,  were the Louis Marx models. Even Mr. Hartnell liked to play with a few of these...

In an odd twist, the toys which the TV programme had spawned would themselves go on to feature in the show - in both Troughton Dalek stories and Pertwee's The Planet of the Daleks, Louis Marx Daleks are used in model shots.

Another toy on offer was a Dalek board game, and there was a Dalek Death Ray - really a gun-shaped torch. Blue Peter asked Ray Cusick to come up with a make-your-own Dalek costume, but there was a commercial version available also. These came in blue or red.

Amusement arcades and fun fairs often had a large Dalek you could sit in and operate the controls - I remember Blackpool ones vividly.
Other Dalek related items that you could have bought in the mid 1960's were Sweetie Cigarettes (they were such innocent and naive times...), ice lollies, Dalek slippers and various other items of apparel.

The Daleks even headed for the pop charts, with The Go-Go's December 1964 "I'm Gonna Spend My Christmas With A Dalek". I don't think Mr Lennon and co. had very much to worry about. He doesn't seem too nonplussed by his drinking companion in this rare little picture - a coming together of the 1960's two great British "Manias".