Links sites tend to overlap each other quite a lot. One good one fills my Fortean devotional each morning. Another I only scan for the photos. This morning, a photographic gold mine. The Smithsonian has flikered swaths of un-copyright restricted photos. Examples may become a Thursday feature here.
This Thursday, anyway.
A woman who loved π. Tatiana Ehrenfest, or Tatyana Alexeyevna Afanasyeva, Mathematician.