I really like airships, especially the old giant rigid airships built by Zeppelin and the U.S. Navy before WWII. I've been studying them for years, reading books and watching documentaries. Recently at work I did a "lunch and learn" on airships and rigid airship history as a fun way to decompress. I also sent along a YouTube playlist of my favorite airship documentaries. In case anyone else wants them, I'm stashing them here for safekeeping.
I'll update this list as I add to my collection, so it'll be a long-lasting bookmark farm.