This very fascinating exercise was started a couple of years ago by a deviantArtist, Napalmnacey. Napalmnacey created the 25 Essential Expressions thread, encouraging others artists to put emotion to picture as a way of help budding illustrators hash out a new character. Many interested deviantArtists soon caught on and these are some of the ones we really liked!
By yoshikimos
by rimorob
By gold-seven