I occasionally discover that there is very little organized information about a set of books that interest me. And so I wind up collecting and organizing the information myself.
Martin Gardner's Collections of "Mathematical Games" Columns
Martin Gardner wrote a monthly column on recreational mathematics for nearly thirty years. The collections of his columns span fifteen titles.
The Incredible Collections of Gustave Verbeek
Gustave Verbeek was an illustrator and cartoonist at the start of the 20th century. His most remarkable cartoon strip was called "The Upside-Downs of Little Lady Lovekins and Old Man Muffaroo".
Books of ambigrams
Includes a list of the many editions of Scott Kim's book.