Trick-or-Treat for digital images w/ "cntnt"
As you may already know, you can add the search string "cntnt" to a WorldCat.org search in order to limit your search to digitized images in library collections.
So if you're still looking for ideas for a costume for Halloween, try this search:
Many of the images are for historical or stage costumes. And while that might not be exactly what you're looking for, it may give you some more creative (and educational) ideas than you'll get from a general web-search for costume images. While those results are certainly vast, I'm not sure how useful hundreds of pictures of people dressed as Darth Vader and pirates are when what you want are interesting brainstorming ideas. Some other thoughts for All Hallows' Eve searches:Folger Shakespeare Library collection for me... with some wonderful watercolors of 36 costume ideas for a production of Romeo and Juliet. Wonderful costume idea fodder and so much more interesting than, well... another Darth Vader.