My favorite posting is "Twas the Night Before Thanksgiving" because he struggled so hard to get that one published and finally found a publisher (the 26th one I think?) who had some sense! Look out how detailed it is - he almost didn't need to paint it in the end, it would have been great in black and white as well.
Who knows how long these treasures will stay online, but I intend to download each book onto my hard drive :-D
***Edit: another link added by the very talented Woody Miller. Thanks Woody!