Today I set up and started adding information to my Web Extras page on my website for THE VISCOUNT'S KISS.
Because the hero, "Buggy" Bromwell, is particularly fascinated by spiders, one of my research missions was to discover what was known about spiders, when. I found a book that addressed that problem exactly, called SPIDERS, MEN AND SCORPIONS by Theodore Savory. It was out of print, but I was able to obtain a copy via abebooks. It wasn't cheap (around $40 by the time shipping was included) but considering I couldn't get it from the library and found it so useful, I don't regret the price.
And there was a bonus: I found out that Little Miss Muffet of nursery rhyme fame might really have existed. She may have been the step-daughter of Dr. Thomas Moufet (or Mouffet or Muffet) who wrote the publication pictured here, Insectorum sive minimorum animalium theatrum, also know as the Theater of Insects.
That's the sort of information I love to find. It makes research not just interesting but fun, and it's the sort of thing I think my readers might enjoy, too.