The V&A Search Collections pages enable cross-searching their wonderful material in imaginative and very visual ways. For ephemera, try poster, ephemera, greetings card, Christmas, private view, menu, bag, programme (Theatre and performance collection), ticket...
You can narrow your searches in all sorts of ways, e.g Ticket brings up lots of metal bottle tickets, but you can limit by Prints, Drawings and Paintings Collections, then by Advertising, Entertainment, Transport etc. It's great to have the wider context of the material though. All with useful Help screens (at the bottom) explaining how to search, view and order images.
A real voyage of discovery: one of my favourite sites.
Librarian of the John Johnson Collection