How about three? :) And they won't be the usual suspects!The "Recommended Reading" on p78 of the Tutorial book was unexpected and made me smile.The use of headers on pages 32-54 of the Referee book is *inspired*, man!! (as is the follow-up)I LOVE the full color paintings in Rules & Magic, but there's something so wonderfully decadent about the B&W on page 73 (PDF p74), so much story in there, that so wonderfully captures "weird", that's gotta be my favorite.
Medusa---without a doubt. Second choice is the two person welcoming committee to hell---the version with the heads.
The swamp scene is my favorite, closely followed by the medusa.
I love the girl melting in the acid.The scummy Robert Plant bard is great, too.Of course, the medusa rocks.The series of pictures depicting the duel is very awesome.Very difficult to narrow it down. It's all quite good.
Medusa still the best...
One piece I enjoyed was the "Where's the hobbit?" image in the player's guide next to the racial description.
While I like the medusa and the decaying skulls a lot (the skulls are very effective in the PDF, when flipping through the pages), I have to say that my two favourite pieces of art are:1) the cover of the Rules & Magic book; and,2) the suicide merchant on PDF page 55.