Over on 2 Warps to Neptune, there is a two part article on the "Dungeons & Dragons Power Cycle" produced by Coleco in 1984. Find Part One here and Part Two here.
Also, on the same blog, there is an article about the handheld D&D pinball games made by Larami in 1983. Check them out here.
Finally, on the blog of the World's Most Dangerous Dungeon Master, he's got an article on the full-sized arcade D&D Pinball Machine here.