An artist who has been very influential on my life and art: Nick Bantock, famous for his Griffin and Sabine series. (Liz introduced me to his work about... 10 years ago?) His art and books are often mail-themed. If you've never heard of him, check out the website. If you've never read Griffin and Sabine, go sit at Borders for a couple hours and read them-- you're in for a treat.
Nick Bantock
