Art & beautiful things:
David Rumsey Map Collection, huge collection of historical maps & atlases
Stanford’s Data Visualization exhibit
NYPL Digital Collections, digitized photographs, illustrations, maps, manuscripts, and other materials from the New York Public Library
TeX Typography Showcase thread of beautiful typography done in LaTeX & Friends
Tex scientific pictures thread of beautiful scientific pictures done in LaTeX & Friends
Smithsonian Open Access open & reusable images and data from Smithsonian collections
National Gallery of Art’s Artworks collection
Web Gallery of Art searchable collection of European art images with by biographies and artwork commentary
Linkpages
Bill Thayer, american history and a lot more
Marginalia Search, explorer for randomly selected websites
Wibly, cool search engine that indexes simple lightweight websites
ooh.directory, collection of blogs
On snot and fonts / Luc Devroye
50 Watts, mid-century book covers & Eastern European illustration
Japanese woodblock print database
The Linkspages at Larsdatter.com
Others
On Sincerity, Joe Carlsmith
On Liars, Michel de Montaigne
The World of Yesterday, Stefan Zweig