The hunt continues. The person Joe ganked it from, elvendude, gave me the original pic he shrank (shrunk?) down, and it's clearly signed by "Humbug." HMMM! The mystery deepens, and I've been searching on "humbug," "elf," "artwork" and other keywords on Google, but no luck yet. Very interesting! I hope I can find the artist eventually.
Edited to add: Here's a link to the full-sized picture.