For those who haven't already stumbled upon it, Sega's Media FTP Server is an interesting visit, providing images, press releases and fact sheets to be used in promoting Sega's games. There's a ton of official artwork available for games ranging from the unreleased back to the days of the Dreamcast. Some of the images are pretty standard, the same ones that have been used repeatedly in every magazine article under the sun, but there are also a few surprises along the way. On occasion, people even dig up games before they're announced.
Check it out here.