As a photography guy, I've long been primarilly interested in original fashion photographs, ala original Vogue photos and by famous photographers. I even once wrote a small, long out-of-print guide to the genre with a retired Vogue photographer. Unlike in other areas, I'm very picky about what I would buy.
Below is my mini-page on the genre
about fashion photographs
As an old film fan, I've also been recently interested in original film photos. RMY Auctions always has a lot of good movie photos, which is in part where my interest was piqued.