My father went to Haverford College in Pennsylvania, and he recently came across a nice article in Haverford's alumni magazine about Theodor Geisel. Now, Geisel is not a Haverford alum...but his agent Herb Cheyette is. I've collected a few choice bits of trivia from the article below, but I encourage you to read the full article for a fond remembrance of Geisel from his friend and agent Herb Cheyette.
Geisel had a closet next to his studio filled with hats sent to him from children around the world, and when struggling with writer's block, he would read mystery novels, sometimes one a day, until he was ready to work again. ...
[Geisel] had also created a painting called "Plethora of Cats" featuring nothing but cat heads, and often relaxed by adding another head to the menagerie. ...
[Geisel was offered a large sum for the use of some old verses in a holiday message for a TV advertiser.]
"...[Geisel] didn't want Dr. Seuss to be connected to a particular religious holiday or a product of which large doses might have uncertain effects on children."
The sponsor, says Cheyette, was "disbelieving and aghast" and reacted by substantially increasing the financial offer. When Geisel still balked, Cheyette stepped in: "I told him his verses consisted of less than 100 words, and if he accepted the deal he would go into the Guinness Book of Records as the writer paid the most money per word." Geisel was silent for a moment, then responded, "I'd rather be in the book as the writer who refused to be paid the most money per word."
Read the full article for more, including the original of the word Seuss and its original pronunciation. We also have a bunch of great Dr. Seuss articles on the mental_floss blog: Stories Behind 10 Dr. Seuss Stories, 5 Stories About Dr. Seuss, The Dr. Seuss Quiz, and Dr. Seuss' Taxidermy Shop.