A coworker at EC clued me in to a great website, The Public Domain Review:
The site's description of itself:
The public domain is a vast commons of material that everyone is free to enjoy, share and build upon without restriction. All works eventually enter the public domain – from classic works of art, music and literature, to abandoned drafts, tentative plans, and overlooked fragments.
The Public Domain Review aspires to become a bounteous gateway into the whopping plenitude that is the public domain, helping our readers to explore this rich terrain by surfacing unusual and obscure works, and offering fresh reflections and unfamiliar angles on material which is more well known.
By providing a curated collection of exotic scraps and marvellous rarities and linking to freely distributable copies of works in online archives and from far flung corners of the web, we hope to encourage readers to further utilise and explore public domain works by themselves.The site seems to mainly focus on books, but also covers film and images. Lots of weird and wonderful documents that few of us would likely ever discover on our own. I've already downloaded English as She is Spoke from 1884, and am enjoying browsing leisurely for other items of interest. Hmm, I'm rather tempted by The Criminal Prosecution and Capital Punishment of Animals from 1906 (animals tried for human crimes) and The Danger of Premature Interment from 1816 (make sure someone is really dead before you bury them).
The site encourages submission of articles about public domain works, and is open to suggestions for works to include.