A short list of products that ship with Debian pre-installed.
NETGEAR ReadyNAS ?1] ?2] shipped with sarge and a modified kernel
Aleutia E2 low power desktop PC shipped with Debian etch on one flash card
http://www.embeddedarm.com/products/board-detail.php?product=TS-7800 TS-7800 ARM9/FPGA developer board
http://excito.com/bubba/technical-specifications.html Bubba Server and Bubba Two "silent servers".
A list of pages where Debian derivatives list products shipped with the derivative preinstalled: